[es6] Don't use the %GetPrototype runtime entry for super calls.

src/runtime/runtime-classes.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/runtime/runtime-utils.h"
 
 #include <stdlib.h>
 #include <limits>
 
 #include "src/arguments.h"
@@ skipping 491 matching lines @@
       Runtime::GetCallerArguments(isolate, 0, &argument_count);
 
   Handle<Object> result;
   ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
       isolate, result, Execution::New(isolate, super_constructor, new_target,
                                       argument_count, arguments.get()));
 
   return *result;
 }
 
+
+RUNTIME_FUNCTION(Runtime_GetSuperConstructor) {
+  SealHandleScope shs(isolate);
+  DCHECK_EQ(1, args.length());
+  CONVERT_ARG_CHECKED(JSFunction, active_function, 0);
+  return active_function->map()->prototype();
+}
+
 }  // namespace internal
 }  // namespace v8