Add %GetCallerJSFunction intrinsic

src/runtime/runtime-internal.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/v8.h"
 
 #include "src/arguments.h"
 #include "src/bootstrapper.h"
 #include "src/debug.h"
 #include "src/messages.h"
@@ skipping 398 matching lines @@
   return isolate->heap()->ToBoolean(FLAG_harmony_tostring);
 }
 
 
 RUNTIME_FUNCTION(Runtime_GetTypeFeedbackVector) {
   SealHandleScope shs(isolate);
   DCHECK(args.length() == 1);
   CONVERT_ARG_CHECKED(JSFunction, function, 0);
   return function->shared()->feedback_vector();
 }
+
+
+RUNTIME_FUNCTION(Runtime_GetCallerJSFunction) {
+  SealHandleScope shs(isolate);
+  StackFrameIterator it(isolate);
+  RUNTIME_ASSERT(it.frame()->type() == StackFrame::STUB);
+  it.Advance();
+  RUNTIME_ASSERT(it.frame()->type() == StackFrame::JAVA_SCRIPT);
+  return JavaScriptFrame::cast(it.frame())->function();
+}
 }  // namespace internal
 }  // namespace v8