diff --git a/js/src/jsdate.cpp b/js/src/jsdate.cpp
index 7b7cc83bbdb..18ad814fec9 100644
--- a/js/src/jsdate.cpp
+++ b/js/src/jsdate.cpp
@@ -3241,3 +3241,50 @@ js_DateGetMsecSinceEpoch(RawObject obj)
     return obj->isDate() ? obj->getDateUTCTime().toNumber() : 0;
 }
 
+
+static const NativeImpl sReadOnlyDateMethods[] = {
+    date_getTime_impl,
+    date_getYear_impl,
+    date_getFullYear_impl,
+    date_getUTCFullYear_impl,
+    date_getMonth_impl,
+    date_getUTCMonth_impl,
+    date_getDate_impl,
+    date_getUTCDate_impl,
+    date_getDay_impl,
+    date_getUTCDay_impl,
+    date_getHours_impl,
+    date_getUTCHours_impl,
+    date_getMinutes_impl,
+    date_getUTCMinutes_impl,
+    date_getUTCSeconds_impl,
+    date_getUTCMilliseconds_impl,
+    date_getTimezoneOffset_impl,
+    date_toGMTString_impl,
+    date_toISOString_impl,
+    date_toLocaleString_impl,
+    date_toLocaleDateString_impl,
+    date_toLocaleTimeString_impl,
+    date_toLocaleFormat_impl,
+    date_toTimeString_impl,
+    date_toDateString_impl,
+    date_toSource_impl,
+    date_toString_impl,
+    date_valueOf_impl
+};
+
+JS_FRIEND_API(bool)
+js::IsReadOnlyDateMethod(IsAcceptableThis test, NativeImpl method)
+{
+    /* Avoid a linear search in the common case by checking the |this| test. */
+    if (test != IsDate)
+        return false;
+
+    /* Linear search, comparing function pointers. */
+    unsigned max = sizeof(sReadOnlyDateMethods) / sizeof(sReadOnlyDateMethods[0]);
+    for (unsigned i = 0; i < max; ++i) {
+        if (method == sReadOnlyDateMethods[i])
+            return true;
+    }
+    return false;
+}
diff --git a/js/src/jsfriendapi.h b/js/src/jsfriendapi.h
index 675ef2412d0..172b2e98869 100644
--- a/js/src/jsfriendapi.h
+++ b/js/src/jsfriendapi.h
@@ -1549,6 +1549,12 @@ IdToJsval(jsid id)
     return IdToValue(id);
 }
 
+extern JS_FRIEND_API(bool)
+IsReadOnlyDateMethod(JS::IsAcceptableThis test, JS::NativeImpl method);
+
+extern JS_FRIEND_API(bool)
+IsTypedArrayThisCheck(JS::IsAcceptableThis test);
+
 } /* namespace js */
 
 #endif /* jsfriendapi_h___ */
diff --git a/js/src/jstypedarray.cpp b/js/src/jstypedarray.cpp
index 392fbb7b5ea..9c77e937c4a 100644
--- a/js/src/jstypedarray.cpp
+++ b/js/src/jstypedarray.cpp
@@ -3424,6 +3424,23 @@ Class TypedArray::protoClasses[TYPE_MAX] = {
     IMPL_TYPED_ARRAY_PROTO_CLASS(Uint8ClampedArray)
 };
 
+#define CHECK(t, a) { if (t == a::IsThisClass) return true; }
+JS_FRIEND_API(bool)
+js::IsTypedArrayThisCheck(JS::IsAcceptableThis test)
+{
+    CHECK(test, Int8Array);
+    CHECK(test, Uint8Array);
+    CHECK(test, Int16Array);
+    CHECK(test, Uint16Array);
+    CHECK(test, Int32Array);
+    CHECK(test, Uint32Array);
+    CHECK(test, Float32Array);
+    CHECK(test, Float64Array);
+    CHECK(test, Uint8ClampedArray);
+    return false;
+}
+#undef CHECK
+
 static JSObject *
 InitArrayBufferClass(JSContext *cx)
 {