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

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 11 matching lines @@
 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 // 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 observationState = %GetObservationState();
 if (IS_UNDEFINED(observationState.observerInfoMap)) {
-  observationState.observerInfoMap = %CreateObjectHashTable();
-  observationState.objectInfoMap = %CreateObjectHashTable();
-  observationState.notifierTargetMap = %CreateObjectHashTable();
+  observationState.observerInfoMap = %ObservationWeakMapCreate();
+  observationState.objectInfoMap = %ObservationWeakMapCreate();
+  observationState.notifierTargetMap = %ObservationWeakMapCreate();
   observationState.pendingObservers = new InternalArray;
   observationState.observerPriority = 0;
 }
 
-function InternalObjectHashTable(tableName) {
-  this.tableName = tableName;
+function ObservationWeakMap(map) {
+  this.map_ = map;
 }
 
-InternalObjectHashTable.prototype = {
+ObservationWeakMap.prototype = {
   get: function(key) {
-    return %ObjectHashTableGet(observationState[this.tableName], key);
+    key = %UnwrapGlobalProxy(key);
+    if (!IS_SPEC_OBJECT(key)) return void 0;
+    return %WeakMapGet(this.map_, key);
   },
   set: function(key, value) {
-    observationState[this.tableName] =
-        %ObjectHashTableSet(observationState[this.tableName], key, value);
+    key = %UnwrapGlobalProxy(key);
+    if (!IS_SPEC_OBJECT(key)) return void 0;
+    %WeakMapSet(this.map_, key, value);
   },
   has: function(key) {
     return !IS_UNDEFINED(this.get(key));
   }
 };
 
-var observerInfoMap = new InternalObjectHashTable('observerInfoMap');
-var objectInfoMap = new InternalObjectHashTable('objectInfoMap');
-var notifierTargetMap = new InternalObjectHashTable('notifierTargetMap');
+var observerInfoMap =
+    new ObservationWeakMap(observationState.observerInfoMap);
+var objectInfoMap = new ObservationWeakMap(observationState.objectInfoMap);
+var notifierTargetMap =
+    new ObservationWeakMap(observationState.notifierTargetMap);
 
 function CreateObjectInfo(object) {
   var info = {
     changeObservers: new InternalArray,
     notifier: null,
   };
   objectInfoMap.set(object, info);
   return info;
 }
 
@@ skipping 152 matching lines @@
     "getNotifier", ObjectGetNotifier,
     "observe", ObjectObserve,
     "unobserve", ObjectUnobserve
   ));
   InstallFunctions(notifierPrototype, DONT_ENUM, $Array(
     "notify", ObjectNotifierNotify
   ));
 }
 
 SetupObjectObserve();