Allow stepping into Object.observe handlers.

src/debug.h

 // Copyright 2012 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.
 
 #ifndef V8_DEBUG_H_
 #define V8_DEBUG_H_
 
 #include "src/allocation.h"
 #include "src/arguments.h"
 #include "src/assembler.h"
@@ skipping 485 matching lines @@
 
   Address restarter_frame_function_pointer_address() {
     Object*** address = &thread_local_.restarter_frame_function_pointer_;
     return reinterpret_cast<Address>(address);
   }
 
   Address step_in_fp_addr() {
     return reinterpret_cast<Address>(&thread_local_.step_into_fp_);
   }
 
+  StepAction last_step_action() { return thread_local_.last_step_action_; }
+
  private:
   explicit Debug(Isolate* isolate);
 
   void UpdateState();
   void Unload();
   void SetNextBreakId() {
     thread_local_.break_id_ = ++thread_local_.break_count_;
   }
 
   // Check whether there are commands in the command queue.
@@ skipping 234 matching lines @@
   // several frames above.
   // There is no calling conventions here, because it never actually gets
   // called, it only gets returned to.
   static void GenerateFrameDropperLiveEdit(MacroAssembler* masm);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_DEBUG_H_