Fix issue with prototype of WeakMap constructor.

The WeakMap constructor didn't have a unique prototype, so it shared one with
Object. All WeakMap functions (including "get" and "set") were installed on
that prototype.

R=rossberg@chromium.org
BUG=v8:1617
TEST=mjsunit/harmony/weakmaps

Review URL: http://codereview.chromium.org/7658008

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@8941 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/weakmap.js

@@ -33,14 +33,13 @@ const $WeakMap = global.WeakMap;
 
 // -------------------------------------------------------------------
 
-// Set the WeakMap function and constructor.
-%SetCode($WeakMap, function(x) {
+function WeakMapConstructor() {
   if (%_IsConstructCall()) {
     %WeakMapInitialize(this);
   } else {
     return new $WeakMap();
   }
-});
+}
 
 
 function WeakMapGet(key) {
@@ -82,6 +81,12 @@ function WeakMapDelete(key) {
 // -------------------------------------------------------------------
 
 function SetupWeakMap() {
+  // Setup the WeakMap constructor function.
+  %SetCode($WeakMap, WeakMapConstructor);
+
+  // Setup the WeakMap prototype object.
+  %FunctionSetPrototype($WeakMap, new $WeakMap());
+
   // Setup the non-enumerable functions on the WeakMap prototype object.
   InstallFunctionsOnHiddenPrototype($WeakMap.prototype, DONT_ENUM, $Array(
     "get", WeakMapGet,

test/mjsunit/harmony/weakmaps.js

@@ -139,6 +139,23 @@ assertTrue(WeakMap.prototype.has instanceof Function)
 assertTrue(WeakMap.prototype.delete instanceof Function)
 
 
+// Regression test for issue 1617: The prototype of the WeakMap constructor
+// needs to be unique (i.e. different from the one of the Object constructor).
+assertFalse(WeakMap.prototype === Object.prototype);
+var o = Object.create({});
+assertFalse("get" in o);
+assertFalse("set" in o);
+assertEquals(undefined, o.get);
+assertEquals(undefined, o.set);
+var o = Object.create({}, { myValue: {
+  value: 10,
+  enumerable: false,
+  configurable: true,
+  writable: true
+}});
+assertEquals(10, o.myValue);
+
+
 // Stress Test
 // There is a proposed stress-test available at the es-discuss mailing list
 // which cannot be reasonably automated.  Check it out by hand if you like: