diff --git a/dom/base/nsGlobalWindow.cpp b/dom/base/nsGlobalWindow.cpp
index c65107ee979..dda717cd2fd 100644
--- a/dom/base/nsGlobalWindow.cpp
+++ b/dom/base/nsGlobalWindow.cpp
@@ -635,7 +635,7 @@ public:
   virtual bool has(JSContext *cx, JS::Handle<JSObject*> proxy,
                    JS::Handle<jsid> id, bool *bp) const override;
   virtual bool get(JSContext *cx, JS::Handle<JSObject*> proxy,
-                   JS::Handle<JSObject*> receiver,
+                   JS::Handle<JS::Value> receiver,
                    JS::Handle<jsid> id,
                    JS::MutableHandle<JS::Value> vp) const override;
   virtual bool set(JSContext *cx, JS::Handle<JSObject*> proxy,
@@ -900,7 +900,7 @@ nsOuterWindowProxy::hasOwn(JSContext *cx, JS::Handle<JSObject*> proxy,
 
 bool
 nsOuterWindowProxy::get(JSContext *cx, JS::Handle<JSObject*> proxy,
-                        JS::Handle<JSObject*> receiver,
+                        JS::Handle<JS::Value> receiver,
                         JS::Handle<jsid> id,
                         JS::MutableHandle<JS::Value> vp) const
 {
diff --git a/dom/bindings/BindingUtils.cpp b/dom/bindings/BindingUtils.cpp
index 7f2dafd6768..9ad52f44684 100644
--- a/dom/bindings/BindingUtils.cpp
+++ b/dom/bindings/BindingUtils.cpp
@@ -1699,8 +1699,8 @@ NativePropertyHooks sEmptyNativePropertyHooks = {
 
 bool
 GetPropertyOnPrototype(JSContext* cx, JS::Handle<JSObject*> proxy,
-                       JS::Handle<jsid> id, bool* found,
-                       JS::MutableHandle<JS::Value> vp)
+                       JS::Handle<JS::Value> receiver, JS::Handle<jsid> id,
+                       bool* found, JS::MutableHandle<JS::Value> vp)
 {
   JS::Rooted<JSObject*> proto(cx);
   if (!js::GetObjectProto(cx, proxy, &proto)) {
@@ -1719,7 +1719,7 @@ GetPropertyOnPrototype(JSContext* cx, JS::Handle<JSObject*> proxy,
     return true;
   }
 
-  return JS_ForwardGetPropertyTo(cx, proto, id, proxy, vp);
+  return JS_ForwardGetPropertyTo(cx, proto, id, receiver, vp);
 }
 
 bool
diff --git a/dom/bindings/BindingUtils.h b/dom/bindings/BindingUtils.h
index 57adbb097f4..c30bf137c5b 100644
--- a/dom/bindings/BindingUtils.h
+++ b/dom/bindings/BindingUtils.h
@@ -1847,8 +1847,8 @@ ThrowConstructorWithoutNew(JSContext* cx, const char* name);
 
 bool
 GetPropertyOnPrototype(JSContext* cx, JS::Handle<JSObject*> proxy,
-                       JS::Handle<jsid> id, bool* found,
-                       JS::MutableHandle<JS::Value> vp);
+                       JS::Handle<JS::Value> receiver, JS::Handle<jsid> id,
+                       bool* found, JS::MutableHandle<JS::Value> vp);
 
 //
 bool
diff --git a/dom/bindings/Codegen.py b/dom/bindings/Codegen.py
index 8706a23577d..08fe9850d1d 100644
--- a/dom/bindings/Codegen.py
+++ b/dom/bindings/Codegen.py
@@ -11039,7 +11039,7 @@ class CGDOMJSProxyHandler_get(ClassMethod):
     def __init__(self, descriptor):
         args = [Argument('JSContext*', 'cx'),
                 Argument('JS::Handle<JSObject*>', 'proxy'),
-                Argument('JS::Handle<JSObject*>', 'receiver'),
+                Argument('JS::Handle<JS::Value>', 'receiver'),
                 Argument('JS::Handle<jsid>', 'id'),
                 Argument('JS::MutableHandle<JS::Value>', 'vp')]
         ClassMethod.__init__(self, "get", "bool", args,
@@ -11094,7 +11094,7 @@ class CGDOMJSProxyHandler_get(ClassMethod):
 
         getOnPrototype = dedent("""
             bool foundOnPrototype;
-            if (!GetPropertyOnPrototype(cx, proxy, id, &foundOnPrototype, vp)) {
+            if (!GetPropertyOnPrototype(cx, proxy, receiver, id, &foundOnPrototype, vp)) {
               return false;
             }
 
diff --git a/js/ipc/JavaScriptBase.h b/js/ipc/JavaScriptBase.h
index db1b603f28d..28c8337706f 100644
--- a/js/ipc/JavaScriptBase.h
+++ b/js/ipc/JavaScriptBase.h
@@ -66,9 +66,8 @@ class JavaScriptBase : public WrapperOwner, public WrapperAnswer, public Base
                       ReturnStatus* rs, bool* bp) {
         return Answer::RecvHasOwn(ObjectId::deserialize(objId), id, rs, bp);
     }
-    bool RecvGet(const uint64_t& objId, const ObjectVariant& receiverVar,
-                   const JSIDVariant& id,
-                   ReturnStatus* rs, JSVariant* result) {
+    bool RecvGet(const uint64_t& objId, const JSVariant& receiverVar, const JSIDVariant& id,
+                 ReturnStatus* rs, JSVariant* result) {
         return Answer::RecvGet(ObjectId::deserialize(objId), receiverVar, id, rs, result);
     }
     bool RecvSet(const uint64_t& objId, const JSIDVariant& id, const JSVariant& value,
@@ -155,8 +154,7 @@ class JavaScriptBase : public WrapperOwner, public WrapperAnswer, public Base
                     ReturnStatus* rs, bool* bp) {
         return Base::SendHasOwn(objId.serialize(), id, rs, bp);
     }
-    bool SendGet(const ObjectId& objId, const ObjectVariant& receiverVar,
-                 const JSIDVariant& id,
+    bool SendGet(const ObjectId& objId, const JSVariant& receiverVar, const JSIDVariant& id,
                  ReturnStatus* rs, JSVariant* result) {
         return Base::SendGet(objId.serialize(), receiverVar, id, rs, result);
     }
diff --git a/js/ipc/PJavaScript.ipdl b/js/ipc/PJavaScript.ipdl
index d8599cffe71..bea7941c0ed 100644
--- a/js/ipc/PJavaScript.ipdl
+++ b/js/ipc/PJavaScript.ipdl
@@ -32,7 +32,7 @@ both:
 
     prio(high) sync Has(uint64_t objId, JSIDVariant id) returns (ReturnStatus rs, bool has);
     prio(high) sync HasOwn(uint64_t objId, JSIDVariant id) returns (ReturnStatus rs, bool has);
-    prio(high) sync Get(uint64_t objId, ObjectVariant receiver, JSIDVariant id) returns (ReturnStatus rs, JSVariant result);
+    prio(high) sync Get(uint64_t objId, JSVariant receiver, JSIDVariant id) returns (ReturnStatus rs, JSVariant result);
     prio(high) sync Set(uint64_t objId, JSIDVariant id, JSVariant value, JSVariant receiver) returns (ReturnStatus rs);
 
     prio(high) sync IsExtensible(uint64_t objId) returns (ReturnStatus rs, bool result);
diff --git a/js/ipc/WrapperAnswer.cpp b/js/ipc/WrapperAnswer.cpp
index 7e84a67e443..ef7f7f2718f 100644
--- a/js/ipc/WrapperAnswer.cpp
+++ b/js/ipc/WrapperAnswer.cpp
@@ -272,7 +272,7 @@ WrapperAnswer::RecvHasOwn(const ObjectId& objId, const JSIDVariant& idVar, Retur
 }
 
 bool
-WrapperAnswer::RecvGet(const ObjectId& objId, const ObjectVariant& receiverVar,
+WrapperAnswer::RecvGet(const ObjectId& objId, const JSVariant& receiverVar,
                        const JSIDVariant& idVar, ReturnStatus* rs, JSVariant* result)
 {
     // We may run scripted getters.
@@ -289,8 +289,8 @@ WrapperAnswer::RecvGet(const ObjectId& objId, const ObjectVariant& receiverVar,
     if (!obj)
         return fail(aes, rs);
 
-    RootedObject receiver(cx, fromObjectVariant(cx, receiverVar));
-    if (!receiver)
+    RootedValue receiver(cx);
+    if (!fromVariant(cx, receiverVar, &receiver))
         return fail(aes, rs);
 
     RootedId id(cx);
diff --git a/js/ipc/WrapperAnswer.h b/js/ipc/WrapperAnswer.h
index 4c01a200b2f..ebb154a7685 100644
--- a/js/ipc/WrapperAnswer.h
+++ b/js/ipc/WrapperAnswer.h
@@ -39,7 +39,7 @@ class WrapperAnswer : public virtual JavaScriptShared
                  ReturnStatus* rs, bool* foundp);
     bool RecvHasOwn(const ObjectId& objId, const JSIDVariant& id,
                     ReturnStatus* rs, bool* foundp);
-    bool RecvGet(const ObjectId& objId, const ObjectVariant& receiverVar,
+    bool RecvGet(const ObjectId& objId, const JSVariant& receiverVar,
                  const JSIDVariant& id,
                  ReturnStatus* rs, JSVariant* result);
     bool RecvSet(const ObjectId& objId, const JSIDVariant& id, const JSVariant& value,
diff --git a/js/ipc/WrapperOwner.cpp b/js/ipc/WrapperOwner.cpp
index f88aa5634e5..97e7160fc4b 100644
--- a/js/ipc/WrapperOwner.cpp
+++ b/js/ipc/WrapperOwner.cpp
@@ -111,7 +111,7 @@ class CPOWProxyHandler : public BaseProxyHandler
                                    ObjectOpResult& result) const override;
     virtual bool isExtensible(JSContext* cx, HandleObject proxy, bool* extensible) const override;
     virtual bool has(JSContext* cx, HandleObject proxy, HandleId id, bool* bp) const override;
-    virtual bool get(JSContext* cx, HandleObject proxy, HandleObject receiver,
+    virtual bool get(JSContext* cx, HandleObject proxy, HandleValue receiver,
                      HandleId id, MutableHandleValue vp) const override;
     virtual bool set(JSContext* cx, JS::HandleObject proxy, JS::HandleId id, JS::HandleValue v,
                      JS::HandleValue receiver, JS::ObjectOpResult& result) const override;
@@ -341,7 +341,7 @@ WrapperOwner::hasOwn(JSContext* cx, HandleObject proxy, HandleId id, bool* bp)
 }
 
 bool
-CPOWProxyHandler::get(JSContext* cx, HandleObject proxy, HandleObject receiver,
+CPOWProxyHandler::get(JSContext* cx, HandleObject proxy, HandleValue receiver,
                       HandleId id, MutableHandleValue vp) const
 {
     FORWARD(get, (cx, proxy, receiver, id, vp));
@@ -458,13 +458,13 @@ WrapperOwner::DOMQI(JSContext* cx, JS::HandleObject proxy, JS::CallArgs& args)
 }
 
 bool
-WrapperOwner::get(JSContext* cx, HandleObject proxy, HandleObject receiver,
+WrapperOwner::get(JSContext* cx, HandleObject proxy, HandleValue receiver,
                   HandleId id, MutableHandleValue vp)
 {
     ObjectId objId = idOf(proxy);
 
-    ObjectVariant receiverVar;
-    if (!toObjectVariant(cx, receiver, &receiverVar))
+    JSVariant receiverVar;
+    if (!toVariant(cx, receiver, &receiverVar))
         return false;
 
     JSIDVariant idVar;
diff --git a/js/ipc/WrapperOwner.h b/js/ipc/WrapperOwner.h
index b35db385129..ac1cccc8cc3 100644
--- a/js/ipc/WrapperOwner.h
+++ b/js/ipc/WrapperOwner.h
@@ -40,7 +40,7 @@ class WrapperOwner : public virtual JavaScriptShared
     bool preventExtensions(JSContext* cx, JS::HandleObject proxy, JS::ObjectOpResult& result);
     bool isExtensible(JSContext* cx, JS::HandleObject proxy, bool* extensible);
     bool has(JSContext* cx, JS::HandleObject proxy, JS::HandleId id, bool* bp);
-    bool get(JSContext* cx, JS::HandleObject proxy, JS::HandleObject receiver,
+    bool get(JSContext* cx, JS::HandleObject proxy, JS::HandleValue receiver,
              JS::HandleId id, JS::MutableHandleValue vp);
     bool set(JSContext* cx, JS::HandleObject proxy, JS::HandleId id, JS::HandleValue v,
              JS::HandleValue receiver, JS::ObjectOpResult& result);
@@ -125,7 +125,7 @@ class WrapperOwner : public virtual JavaScriptShared
                          ReturnStatus* rs, bool* bp) = 0;
     virtual bool SendHasOwn(const ObjectId& objId, const JSIDVariant& id,
                             ReturnStatus* rs, bool* bp) = 0;
-    virtual bool SendGet(const ObjectId& objId, const ObjectVariant& receiverVar,
+    virtual bool SendGet(const ObjectId& objId, const JSVariant& receiverVar,
                          const JSIDVariant& id,
                          ReturnStatus* rs, JSVariant* result) = 0;
     virtual bool SendSet(const ObjectId& objId, const JSIDVariant& id, const JSVariant& value,
diff --git a/js/src/jsapi.cpp b/js/src/jsapi.cpp
index 8636c83d477..66951d046d4 100644
--- a/js/src/jsapi.cpp
+++ b/js/src/jsapi.cpp
@@ -2920,12 +2920,16 @@ JS_GetPropertyDescriptor(JSContext* cx, HandleObject obj, const char* name,
 JS_PUBLIC_API(bool)
 JS_GetPropertyById(JSContext* cx, HandleObject obj, HandleId id, MutableHandleValue vp)
 {
-    return JS_ForwardGetPropertyTo(cx, obj, id, obj, vp);
+    AssertHeapIsIdle(cx);
+    CHECK_REQUEST(cx);
+    assertSameCompartment(cx, obj, id);
+
+    return GetProperty(cx, obj, obj, id, vp);
 }
 
 JS_PUBLIC_API(bool)
-JS_ForwardGetPropertyTo(JSContext* cx, JS::HandleObject obj, JS::HandleId id, JS::HandleObject onBehalfOf,
-                        JS::MutableHandleValue vp)
+JS_ForwardGetPropertyTo(JSContext* cx, HandleObject obj, HandleId id, HandleValue onBehalfOf,
+                        MutableHandleValue vp)
 {
     AssertHeapIsIdle(cx);
     CHECK_REQUEST(cx);
@@ -2935,9 +2939,13 @@ JS_ForwardGetPropertyTo(JSContext* cx, JS::HandleObject obj, JS::HandleId id, JS
 }
 
 JS_PUBLIC_API(bool)
-JS_GetElement(JSContext* cx, HandleObject objArg, uint32_t index, MutableHandleValue vp)
+JS_GetElement(JSContext* cx, HandleObject obj, uint32_t index, MutableHandleValue vp)
 {
-    return JS_ForwardGetElementTo(cx, objArg, index, objArg, vp);
+    AssertHeapIsIdle(cx);
+    CHECK_REQUEST(cx);
+    assertSameCompartment(cx, obj);
+
+    return GetElement(cx, obj, obj, index, vp);
 }
 
 JS_PUBLIC_API(bool)
diff --git a/js/src/jsapi.h b/js/src/jsapi.h
index c4a1c980342..ddc6afbb5fc 100644
--- a/js/src/jsapi.h
+++ b/js/src/jsapi.h
@@ -2853,7 +2853,7 @@ extern JS_PUBLIC_API(bool)
 JS_GetPropertyById(JSContext* cx, JS::HandleObject obj, JS::HandleId id, JS::MutableHandleValue vp);
 
 extern JS_PUBLIC_API(bool)
-JS_ForwardGetPropertyTo(JSContext* cx, JS::HandleObject obj, JS::HandleId id, JS::HandleObject onBehalfOf,
+JS_ForwardGetPropertyTo(JSContext* cx, JS::HandleObject obj, JS::HandleId id, JS::HandleValue onBehalfOf,
                         JS::MutableHandleValue vp);
 
 extern JS_PUBLIC_API(bool)
diff --git a/js/xpconnect/src/Sandbox.cpp b/js/xpconnect/src/Sandbox.cpp
index 8a44da5a2af..6cbe739b237 100644
--- a/js/xpconnect/src/Sandbox.cpp
+++ b/js/xpconnect/src/Sandbox.cpp
@@ -828,7 +828,7 @@ xpc::SandboxProxyHandler::hasOwn(JSContext* cx, JS::Handle<JSObject*> proxy,
 
 bool
 xpc::SandboxProxyHandler::get(JSContext* cx, JS::Handle<JSObject*> proxy,
-                              JS::Handle<JSObject*> receiver,
+                              JS::Handle<JS::Value> receiver,
                               JS::Handle<jsid> id,
                               JS::MutableHandle<Value> vp) const
 {
diff --git a/js/xpconnect/wrappers/AddonWrapper.cpp b/js/xpconnect/wrappers/AddonWrapper.cpp
index e0fdd960568..bfc3e2e5937 100644
--- a/js/xpconnect/wrappers/AddonWrapper.cpp
+++ b/js/xpconnect/wrappers/AddonWrapper.cpp
@@ -169,7 +169,7 @@ AddonWrapper<Base>::getOwnPropertyDescriptor(JSContext* cx, HandleObject wrapper
 
 template<typename Base>
 bool
-AddonWrapper<Base>::get(JSContext* cx, JS::Handle<JSObject*> wrapper, JS::Handle<JSObject*> receiver,
+AddonWrapper<Base>::get(JSContext* cx, JS::Handle<JSObject*> wrapper, JS::Handle<Value> receiver,
                         JS::Handle<jsid> id, JS::MutableHandle<JS::Value> vp) const
 {
     Rooted<JSPropertyDescriptor> desc(cx);
@@ -180,10 +180,7 @@ AddonWrapper<Base>::get(JSContext* cx, JS::Handle<JSObject*> wrapper, JS::Handle
         return Base::get(cx, wrapper, receiver, id, vp);
 
     if (desc.getter()) {
-        MOZ_ASSERT(desc.hasGetterObject());
-        AutoValueVector args(cx);
-        RootedValue fval(cx, ObjectValue(*desc.getterObject()));
-        return JS_CallFunctionValue(cx, receiver, fval, args, vp);
+        return Call(cx, receiver, desc.getterObject(), HandleValueArray::empty(), vp);
     } else {
         vp.set(desc.value());
         return true;
diff --git a/js/xpconnect/wrappers/AddonWrapper.h b/js/xpconnect/wrappers/AddonWrapper.h
index 8515f71ad17..5d1a324c3da 100644
--- a/js/xpconnect/wrappers/AddonWrapper.h
+++ b/js/xpconnect/wrappers/AddonWrapper.h
@@ -36,7 +36,7 @@ class AddonWrapper : public Base {
                                 JS::ObjectOpResult& result) const override;
     virtual bool delete_(JSContext* cx, JS::HandleObject proxy, JS::HandleId id,
                          JS::ObjectOpResult& result) const override;
-    virtual bool get(JSContext* cx, JS::Handle<JSObject*> wrapper, JS::Handle<JSObject*> receiver,
+    virtual bool get(JSContext* cx, JS::Handle<JSObject*> wrapper, JS::Handle<JS::Value> receiver,
                      JS::Handle<jsid> id, JS::MutableHandle<JS::Value> vp) const override;
     virtual bool set(JSContext* cx, JS::HandleObject wrapper, JS::HandleId id, JS::HandleValue v,
                      JS::HandleValue receiver, JS::ObjectOpResult& result) const override;
diff --git a/js/xpconnect/wrappers/WaiveXrayWrapper.cpp b/js/xpconnect/wrappers/WaiveXrayWrapper.cpp
index 3ad47217be0..7e78c122c24 100644
--- a/js/xpconnect/wrappers/WaiveXrayWrapper.cpp
+++ b/js/xpconnect/wrappers/WaiveXrayWrapper.cpp
@@ -50,8 +50,7 @@ WaiveXrayWrapper::getOwnPropertyDescriptor(JSContext* cx, HandleObject wrapper,
 }
 
 bool
-WaiveXrayWrapper::get(JSContext* cx, HandleObject wrapper,
-                      HandleObject receiver, HandleId id,
+WaiveXrayWrapper::get(JSContext* cx, HandleObject wrapper, HandleValue receiver, HandleId id,
                       MutableHandleValue vp) const
 {
     return CrossCompartmentWrapper::get(cx, wrapper, receiver, id, vp) &&
diff --git a/js/xpconnect/wrappers/WaiveXrayWrapper.h b/js/xpconnect/wrappers/WaiveXrayWrapper.h
index 4ecef0a905a..eeb1507dbb3 100644
--- a/js/xpconnect/wrappers/WaiveXrayWrapper.h
+++ b/js/xpconnect/wrappers/WaiveXrayWrapper.h
@@ -22,7 +22,7 @@ class WaiveXrayWrapper : public js::CrossCompartmentWrapper {
                                           JS::MutableHandle<JSPropertyDescriptor> desc) const override;
     virtual bool getPrototype(JSContext* cx, JS::Handle<JSObject*> wrapper,
                               JS::MutableHandle<JSObject*> protop) const override;
-    virtual bool get(JSContext* cx, JS::Handle<JSObject*> wrapper, JS::Handle<JSObject*> receiver,
+    virtual bool get(JSContext* cx, JS::Handle<JSObject*> wrapper, JS::Handle<JS::Value> receiver,
                      JS::Handle<jsid> id, JS::MutableHandle<JS::Value> vp) const override;
     virtual bool call(JSContext* cx, JS::Handle<JSObject*> wrapper,
                       const JS::CallArgs& args) const override;
diff --git a/js/xpconnect/wrappers/XrayWrapper.cpp b/js/xpconnect/wrappers/XrayWrapper.cpp
index 9b4d6df2abc..eae06fb7ca9 100644
--- a/js/xpconnect/wrappers/XrayWrapper.cpp
+++ b/js/xpconnect/wrappers/XrayWrapper.cpp
@@ -2092,13 +2092,18 @@ XrayWrapper<Base, Traits>::delete_(JSContext* cx, HandleObject wrapper,
 template <typename Base, typename Traits>
 bool
 XrayWrapper<Base, Traits>::get(JSContext* cx, HandleObject wrapper,
-                               HandleObject receiver, HandleId id,
+                               HandleValue receiver, HandleId id,
                                MutableHandleValue vp) const
 {
     // Skip our Base if it isn't already ProxyHandler.
     // NB: None of the functions we call are prepared for the receiver not
     // being the wrapper, so ignore the receiver here.
-    return js::BaseProxyHandler::get(cx, wrapper, Traits::HasPrototype ? receiver : wrapper, id, vp);
+    RootedValue thisv(cx);
+    if (Traits::HasPrototype)
+      thisv = receiver;
+    else
+      thisv.setObject(*wrapper);
+    return js::BaseProxyHandler::get(cx, wrapper, thisv, id, vp);
 }
 
 template <typename Base, typename Traits>
diff --git a/js/xpconnect/wrappers/XrayWrapper.h b/js/xpconnect/wrappers/XrayWrapper.h
index d233372929c..bb0b7178140 100644
--- a/js/xpconnect/wrappers/XrayWrapper.h
+++ b/js/xpconnect/wrappers/XrayWrapper.h
@@ -446,7 +446,7 @@ class XrayWrapper : public Base {
     virtual bool isExtensible(JSContext* cx, JS::Handle<JSObject*> wrapper, bool* extensible) const override;
     virtual bool has(JSContext* cx, JS::Handle<JSObject*> wrapper, JS::Handle<jsid> id,
                      bool* bp) const override;
-    virtual bool get(JSContext* cx, JS::Handle<JSObject*> wrapper, JS::Handle<JSObject*> receiver,
+    virtual bool get(JSContext* cx, JS::Handle<JSObject*> wrapper, JS::HandleValue receiver,
                      JS::Handle<jsid> id, JS::MutableHandle<JS::Value> vp) const override;
     virtual bool set(JSContext* cx, JS::Handle<JSObject*> wrapper, JS::Handle<jsid> id,
                      JS::Handle<JS::Value> v, JS::Handle<JS::Value> receiver,
@@ -520,7 +520,7 @@ public:
     // which implement them in terms of lower-level methods.
     virtual bool has(JSContext* cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id,
                      bool* bp) const override;
-    virtual bool get(JSContext* cx, JS::Handle<JSObject*> proxy, JS::Handle<JSObject*> receiver,
+    virtual bool get(JSContext* cx, JS::Handle<JSObject*> proxy, JS::HandleValue receiver,
                      JS::Handle<jsid> id, JS::MutableHandle<JS::Value> vp) const override;
     virtual bool set(JSContext* cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id,
                      JS::Handle<JS::Value> v, JS::Handle<JS::Value> receiver,