Refactor JavaScriptFrame::function() to return a JSFunction* and remove associated casts.

src/frames-inl.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 256 matching lines @@
 inline void JavaScriptFrame::set_receiver(Object* value) {
   Memory::Object_at(GetParameterSlot(-1)) = value;
 }
 
 
 inline bool JavaScriptFrame::has_adapted_arguments() const {
   return IsArgumentsAdaptorFrame(caller_fp());
 }
 
 
-inline Object* JavaScriptFrame::function() const {
-  Object* result = function_slot_object();
-  ASSERT(result->IsJSFunction());
-  return result;
+inline JSFunction* JavaScriptFrame::function() const {
+  return JSFunction::cast(function_slot_object());
 }
 
 
 inline StubFrame::StubFrame(StackFrameIteratorBase* iterator)
     : StandardFrame(iterator) {
 }
 
 
 inline OptimizedFrame::OptimizedFrame(StackFrameIteratorBase* iterator)
     : JavaScriptFrame(iterator) {
@@ skipping 48 matching lines @@
 inline JavaScriptFrame* SafeStackFrameIterator::frame() const {
   ASSERT(!done());
   ASSERT(frame_->is_java_script());
   return static_cast<JavaScriptFrame*>(frame_);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_FRAMES_INL_H_