Move (uppercase) JS builtins from js builtins object to native context.

src/contexts.cc

Index: src/contexts.cc
diff --git a/src/contexts.cc b/src/contexts.cc
index 0e89821c7f683e63517c5f0d003aac3d3896e1a4..37021ac7f67f789e33bdf6f91d876fc99eb4c551 100644
--- a/src/contexts.cc
+++ b/src/contexts.cc
@@ -554,6 +554,16 @@ int Context::IntrinsicIndexForName(Handle<String> string) {
 #undef COMPARE_NAME
 
 
+bool Context::IsJSBuiltin(Handle<Context> native_context,
+                          Handle<JSFunction> function) {
+#define COMPARE_FUNCTION(index, type, name) \
+  if (*function == native_context->get(index)) return true;
+  NATIVE_CONTEXT_JS_BUILTINS(COMPARE_FUNCTION);
+#undef COMPARE_FUNCTION
+  return false;
+}
+
+
 #ifdef DEBUG
 bool Context::IsBootstrappingOrValidParentContext(
     Object* object, Context* child) {