Fix call stack sampling for the case when native callback invokes JS function

src/frames.h

Index: src/frames.h
diff --git a/src/frames.h b/src/frames.h
index 7e667a6acd293e9509348522d676f21aac1e72d8..5a5c34c1d76187ea2aa502450e186f2da1f4cf6d 100644
--- a/src/frames.h
+++ b/src/frames.h
@@ -47,6 +47,7 @@ int JSCallerSavedCode(int n);
 
 
 // Forward declarations.
+class ExternalCallbackScope;
 class StackFrameIteratorBase;
 class ThreadLocalTop;
 class Isolate;
@@ -883,7 +884,7 @@ class SafeStackFrameIterator: public StackFrameIteratorBase {
                          Address fp, Address sp,
                          Address js_entry_sp);
 
-  inline JavaScriptFrame* frame() const;
+  inline StackFrame* frame() const;
   void Advance();
 
   StackFrame::Type top_frame_type() const { return top_frame_type_; }
@@ -902,6 +903,7 @@ class SafeStackFrameIterator: public StackFrameIteratorBase {
   const Address low_bound_;
   const Address high_bound_;
   StackFrame::Type top_frame_type_;
+  ExternalCallbackScope* external_callback_scope_;
 };