Expose the GC under a name that is less collision prone than window.gc.

src/extensions/gc-extension.h

Index: src/extensions/gc-extension.h
diff --git a/src/extensions/gc-extension.h b/src/extensions/gc-extension.h
index 06ea4ed21a63d40db4f1aebfd5acd165e675affe..54b865adf75335d42ac12415cea19f5f72cbca20 100644
--- a/src/extensions/gc-extension.h
+++ b/src/extensions/gc-extension.h
@@ -35,13 +35,11 @@ namespace internal {
 
 class GCExtension : public v8::Extension {
  public:
-  GCExtension() : v8::Extension("v8/gc", kSource) {}
+  explicit GCExtension(const char* source) : v8::Extension("v8/gc", source) {}
   virtual v8::Handle<v8::FunctionTemplate> GetNativeFunction(
       v8::Handle<v8::String> name);
   static v8::Handle<v8::Value> GC(const v8::Arguments& args);
   static void Register();
- private:
-  static const char* const kSource;
 };
 
 } }  // namespace v8::internal