Preliminary Harmony weak maps API implementation.

src/bootstrapper.cc

Index: src/bootstrapper.cc
diff --git a/src/bootstrapper.cc b/src/bootstrapper.cc
index 8cca5614b002d3db55a3f1b09aef85b932b073c8..8d134279533a86375de8062972032d4f8de8bc89 100644
--- a/src/bootstrapper.cc
+++ b/src/bootstrapper.cc
@@ -1680,6 +1680,11 @@ bool Genesis::InstallExperimentalNatives() {
                "native proxy.js") == 0) {
       if (!CompileExperimentalBuiltin(isolate(), i)) return false;
     }
+    if (FLAG_harmony_weakmaps &&
+        strcmp(ExperimentalNatives::GetScriptName(i).start(),
+               "native weakmap.js") == 0) {
+      if (!CompileExperimentalBuiltin(isolate(), i)) return false;
+    }
   }
 
   InstallExperimentalNativeFunctions();
@@ -2169,6 +2174,17 @@ Genesis::Genesis(Isolate* isolate,
     isolate->counters()->contexts_created_from_scratch()->Increment();
   }
 
+  // TODO(mstarzinger): Move this into Genesis::InitializeGlobal once we no
+  // longer need to live behind a flag, so WeakMap gets added to the snapshot.
+  Handle<JSObject> global = Handle<JSObject>(global_context()->global());
+  if (FLAG_harmony_weakmaps) {  // -- W e a k M a p
+     Handle<JSFunction> weakmap_fun =
+        InstallFunction(global, "WeakMap", JS_WEAKMAP_TYPE, JSWeakMap::kSize,
+                        isolate->initial_object_prototype(),
+                        Builtins::kIllegal, true);
+    //global_context()->set_weakmap_function(*weakmap_fun);
+  }
+
   // Install experimental natives.
   if (!InstallExperimentalNatives()) return;