Implement WeakMap.prototype.clear function.

src/collection.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 277 matching lines @@
     throw MakeTypeError('incompatible_method_receiver',
                         ['WeakMap.prototype.delete', this]);
   }
   if (!(IS_SPEC_OBJECT(key) || IS_SYMBOL(key))) {
     throw %MakeTypeError('invalid_weakmap_key', [this, key]);
   }
   return %WeakMapDelete(this, key);
 }
 
 
+function WeakMapClear() {
+  if (!IS_WEAKMAP(this)) {
+    throw MakeTypeError('incompatible_method_receiver',
+                        ['WeakMap.prototype.clear', this]);
+  }
+  // Replace the internal table with a new empty table.
+  %WeakMapInitialize(this);
+}
+
+
 // -------------------------------------------------------------------
 
 function SetUpWeakMap() {
   %CheckIsBootstrapping();
 
   %SetCode($WeakMap, WeakMapConstructor);
   %FunctionSetPrototype($WeakMap, new $Object());
   %SetProperty($WeakMap.prototype, "constructor", $WeakMap, DONT_ENUM);
 
   // Set up the non-enumerable functions on the WeakMap prototype object.
   InstallFunctions($WeakMap.prototype, DONT_ENUM, $Array(
     "get", WeakMapGet,
     "set", WeakMapSet,
     "has", WeakMapHas,
-    "delete", WeakMapDelete
+    "delete", WeakMapDelete,
+    "clear", WeakMapClear
   ));
 }
 
 SetUpWeakMap();