Object.observe: use JSWeakMaps instead of raw ObjectHashTables in observation state

src/runtime.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 315 matching lines @@
   F(WeakMapGet, 2, 1) \
   F(WeakMapHas, 2, 1) \
   F(WeakMapDelete, 2, 1) \
   F(WeakMapSet, 3, 1) \
   \
   /* Harmony observe */ \
   F(IsObserved, 1, 1) \
   F(SetIsObserved, 2, 1) \
   F(SetObserverDeliveryPending, 0, 1) \
   F(GetObservationState, 0, 1) \
-  F(CreateObjectHashTable, 0, 1) \
-  F(ObjectHashTableGet, 2, 1) \
-  F(ObjectHashTableSet, 3, 1) \
+  F(ObservationWeakMapCreate, 0, 1) \
+  F(UnwrapGlobalProxy, 1, 1) \
   \
   /* Statements */ \
   F(NewClosure, 3, 1) \
   F(NewObject, 1, 1) \
   F(NewObjectFromBound, 1, 1) \
   F(FinalizeInstanceSize, 1, 1) \
   F(Throw, 1, 1) \
   F(ReThrow, 1, 1) \
   F(ThrowReferenceError, 1, 1) \
   F(ThrowNotDateError, 0, 1) \
@@ skipping 362 matching lines @@
 //---------------------------------------------------------------------------
 // Constants used by interface to runtime functions.
 
 class DeclareGlobalsEvalFlag:     public BitField<bool,         0, 1> {};
 class DeclareGlobalsNativeFlag:   public BitField<bool,         1, 1> {};
 class DeclareGlobalsLanguageMode: public BitField<LanguageMode, 2, 2> {};
 
 } }  // namespace v8::internal
 
 #endif  // V8_RUNTIME_H_