Store Object.observe state per-isolate rather than per-context

src/object-observe.js

 // 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 12 matching lines @@
 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 "use strict";
 
 var InternalObjectIsFrozen = $Object.isFrozen;
 var InternalObjectFreeze = $Object.freeze;
 
-var InternalWeakMapProto = {
-  __proto__: null,
-  set: $WeakMap.prototype.set,
-  get: $WeakMap.prototype.get,
-  has: $WeakMap.prototype.has
+var observationState = %GetObservationState();
+if (IS_UNDEFINED(observationState.observerInfoMap)) {
+  observationState.observerInfoMap = %CreateObjectHashTable();
+  observationState.objectInfoMap = %CreateObjectHashTable();
 }
 
-function createInternalWeakMap() {
-  var map = new $WeakMap;
-  map.__proto__ = InternalWeakMapProto;
-  return map;
+function InternalObjectHashTable(table) {
+  this.table = table;
 }
 
-var observerInfoMap = createInternalWeakMap();
-var objectInfoMap = createInternalWeakMap();
+InternalObjectHashTable.prototype = {
+  get: function(key) {
+    return %ObjectHashTableGet(this.table, key);
+  },
+  set: function(key, value) {
+    return %ObjectHashTableSet(this.table, key, value);
+  },
+  has: function(key) {
+    return %ObjectHashTableHas(this.table, key);
+  }
+};
+
+var observerInfoMap = new InternalObjectHashTable(
+    observationState.observerInfoMap);
+var objectInfoMap = new InternalObjectHashTable(observationState.objectInfoMap);
 
 function ObjectObserve(object, callback) {
   if (!IS_SPEC_OBJECT(object))
     throw MakeTypeError("observe_non_object", ["observe"]);
   if (!IS_SPEC_FUNCTION(callback))
     throw MakeTypeError("observe_non_function", ["observe"]);
   if (InternalObjectIsFrozen(callback))
     throw MakeTypeError("observe_callback_frozen");
 
   if (!observerInfoMap.has(callback)) {
@@ skipping 107 matching lines @@
   %CheckIsBootstrapping();
   InstallFunctions($Object, DONT_ENUM, $Array(
     "deliverChangeRecords", ObjectDeliverChangeRecords,
     "notify", ObjectNotify,  // TODO: Remove when getNotifier is implemented.
     "observe", ObjectObserve,
     "unobserve", ObjectUnobserve
   ));
 }
 
 SetupObjectObserve();