diff --git a/dom/bindings/BindingUtils.cpp b/dom/bindings/BindingUtils.cpp
index 5ee0a608772..49aefd24d4b 100644
--- a/dom/bindings/BindingUtils.cpp
+++ b/dom/bindings/BindingUtils.cpp
@@ -1947,9 +1947,10 @@ InterfaceHasInstance(JSContext* cx, int prototypeID, int depth,
 }
 
 bool
-ReportLenientThisUnwrappingFailure(JSContext* cx, JS::Handle<JSObject*> obj)
+ReportLenientThisUnwrappingFailure(JSContext* cx, JSObject* obj)
 {
-  GlobalObject global(cx, obj);
+  JS::Rooted<JSObject*> rootedObj(cx, obj);
+  GlobalObject global(cx, rootedObj);
   if (global.Failed()) {
     return false;
   }
diff --git a/dom/bindings/BindingUtils.h b/dom/bindings/BindingUtils.h
index f07565c29f5..c383e156f5a 100644
--- a/dom/bindings/BindingUtils.h
+++ b/dom/bindings/BindingUtils.h
@@ -2062,7 +2062,7 @@ InterfaceHasInstance(JSContext* cx, int prototypeID, int depth,
 // Helper for lenient getters/setters to report to console.  If this
 // returns false, we couldn't even get a global.
 bool
-ReportLenientThisUnwrappingFailure(JSContext* cx, JS::Handle<JSObject*> obj);
+ReportLenientThisUnwrappingFailure(JSContext* cx, JSObject* obj);
 
 inline JSObject*
 GetUnforgeableHolder(JSObject* aGlobal, prototypes::ID aId)
diff --git a/dom/bindings/Codegen.py b/dom/bindings/Codegen.py
index 341d7eca50c..ff653942ebf 100644
--- a/dom/bindings/Codegen.py
+++ b/dom/bindings/Codegen.py
@@ -5321,9 +5321,18 @@ class CGAbstractBindingMethod(CGAbstractStaticMethod):
     |this| object.  Subclasses are expected to override the generate_code
     function to do the rest of the work.  This function should return a
     CGThing which is already properly indented.
+
+    getThisObj should be code for getting a JSObject* for the binding
+    object.  If this is None, we will auto-generate code based on
+    descriptor to do the right thing.  "" can be passed in if the
+    binding object is already stored in 'obj'.
+
+    callArgs should be code for getting a JS::CallArgs into a variable
+    called 'args'.  This can be "" if there is already such a variable
+    around.
     """
     def __init__(self, descriptor, name, args, unwrapFailureCode=None,
-                 getThisObj="args.computeThis(cx).toObjectOrNull()",
+                 getThisObj=None,
                  callArgs="JS::CallArgs args = JS::CallArgsFromVp(argc, vp);"):
         CGAbstractStaticMethod.__init__(self, descriptor, name, "bool", args)
 
@@ -5331,7 +5340,26 @@ class CGAbstractBindingMethod(CGAbstractStaticMethod):
             self.unwrapFailureCode = 'return ThrowErrorMessage(cx, MSG_THIS_DOES_NOT_IMPLEMENT_INTERFACE, "Value", "%s");' % descriptor.interface.identifier.name
         else:
             self.unwrapFailureCode = unwrapFailureCode
-        self.getThisObj = getThisObj
+
+        if getThisObj == "":
+            self.getThisObj = None
+        else:
+            if getThisObj is None:
+                if descriptor.interface.isOnGlobalProtoChain():
+                    ensureCondition = "!args.thisv().isNullOrUndefined() && !args.thisv().isObject()"
+                    getThisObj = "args.thisv().isObject() ? &args.thisv().toObject() : js::GetGlobalForObjectCrossCompartment(&args.callee())"
+                else:
+                    ensureCondition = "!args.thisv().isObject()"
+                    getThisObj = "&args.thisv().toObject()"
+                ensureThisObj = CGIfWrapper(CGGeneric(self.unwrapFailureCode),
+                                            ensureCondition)
+            else:
+                ensureThisObj = None
+            self.getThisObj = CGList(
+                [ensureThisObj,
+                 CGGeneric("JS::RootedObject obj(cx, %s);\n" %
+                           getThisObj)],
+                "\n")
         self.callArgs = callArgs
 
     def definition_body(self):
@@ -5341,10 +5369,7 @@ class CGAbstractBindingMethod(CGAbstractStaticMethod):
         # consumption by CastableObjectUnwrapper.
         getThis = CGList([
                 CGGeneric(self.callArgs) if self.callArgs != "" else None,
-                CGGeneric("JS::RootedObject obj(cx, %s);\n"
-                          "if (!obj) {\n"
-                          "  return false;\n"
-                          "}" % self.getThisObj) if self.getThisObj else None,
+                self.getThisObj,
                 CGGeneric("%s* self;" % self.descriptor.nativeType)
                 ], "\n")
         unwrapThis = CGGeneric(
@@ -5585,7 +5610,7 @@ class CGGenericGetter(CGAbstractBindingMethod):
             name = "genericLenientGetter"
             unwrapFailureCode = (
                 "MOZ_ASSERT(!JS_IsExceptionPending(cx));\n"
-                "if (!ReportLenientThisUnwrappingFailure(cx, obj)) {\n"
+                "if (!ReportLenientThisUnwrappingFailure(cx, &args.callee())) {\n"
                 "  return false;\n"
                 "}\n"
                 "args.rval().set(JS::UndefinedValue());\n"
@@ -5665,7 +5690,7 @@ class CGGenericSetter(CGAbstractBindingMethod):
             name = "genericLenientSetter"
             unwrapFailureCode = (
                 "MOZ_ASSERT(!JS_IsExceptionPending(cx));\n"
-                "if (!ReportLenientThisUnwrappingFailure(cx, obj)) {\n"
+                "if (!ReportLenientThisUnwrappingFailure(cx, &args.callee())) {\n"
                 "  return false;\n"
                 "}\n"
                 "args.rval().set(JS::UndefinedValue());\n"