Remove support for Object.observe

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index d4590e25fecc35ea1b995fd334cc03a76f02d5fe..326bb24b76935abee9c0a4d8b36ec1db766bbf7c 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -2395,9 +2395,6 @@ class JSObject: public JSReceiver {
 
   static bool IsExtensible(Handle<JSObject> object);
 
-  // Called the first time an object is observed with ES7 Object.observe.
-  static void SetObserved(Handle<JSObject> object);
-
   // Copy object.
   enum DeepCopyHints { kNoHints = 0, kObjectIsShallow = 1 };
 
@@ -2498,11 +2495,6 @@ class JSObject: public JSReceiver {
 
   typedef FlexibleBodyDescriptor<JSReceiver::kPropertiesOffset> BodyDescriptor;
 
-  // Enqueue change record for Object.observe. May cause GC.
-  MUST_USE_RESULT static MaybeHandle<Object> EnqueueChangeRecord(
-      Handle<JSObject> object, const char* type, Handle<Name> name,
-      Handle<Object> old_value);
-
   // Gets the number of currently used elements.
   int GetFastElementsUsage();
 
@@ -2559,10 +2551,6 @@ class JSObject: public JSReceiver {
   MUST_USE_RESULT static Maybe<bool> PreventExtensionsWithTransition(
       Handle<JSObject> object, ShouldThrow should_throw);
 
-  MUST_USE_RESULT static Maybe<bool> SetPrototypeUnobserved(
-      Handle<JSObject> object, Handle<Object> value, bool from_javascript,
-      ShouldThrow should_throw);
-
   DISALLOW_IMPLICIT_CONSTRUCTORS(JSObject);
 };
 
@@ -5733,10 +5721,6 @@ class Map: public HeapObject {
   inline void set_is_undetectable();
   inline bool is_undetectable();
 
-  // Tells whether the instance has a call-as-function handler.
-  inline void set_is_observed();
-  inline bool is_observed();
-
   // Tells whether the instance has a [[Call]] internal method.
   // This property is implemented according to ES6, section 7.2.3.
   inline void set_is_callable();
@@ -5975,8 +5959,6 @@ class Map: public HeapObject {
                                     FunctionKind kind);
 
 
-  static Handle<Map> CopyForObserved(Handle<Map> map);
-
   static Handle<Map> CopyForPreventExtensions(Handle<Map> map,
                                               PropertyAttributes attrs_to_add,
                                               Handle<Symbol> transition_marker,
@@ -6172,9 +6154,9 @@ class Map: public HeapObject {
   static const int kHasNamedInterceptor = 2;
   static const int kHasIndexedInterceptor = 3;
   static const int kIsUndetectable = 4;
-  static const int kIsObserved = 5;
-  static const int kIsAccessCheckNeeded = 6;
-  static const int kIsConstructor = 7;
+  static const int kIsAccessCheckNeeded = 5;
+  static const int kIsConstructor = 6;
+  // Bit 7 is free.
 
   // Bit positions for bit field 2
   static const int kIsExtensible = 0;
@@ -10167,9 +10149,6 @@ class JSArray: public JSObject {
   inline bool AllowsSetLength();
 
   static void SetLength(Handle<JSArray> array, uint32_t length);
-  // Same as above but will also queue splice records if |array| is observed.
-  static MaybeHandle<Object> ObservableSetLength(Handle<JSArray> array,
-                                                 uint32_t length);
 
   // Set the content of the array to the content of storage.
   static inline void SetContent(Handle<JSArray> array,