Introduce intrinsic to expose debug state to generated code.

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 487 matching lines @@
   inline bool has_break_points() const { return has_break_points_; }
   inline bool in_debug_scope() const {
     return thread_local_.current_debug_scope_ != NULL;
   }
   void set_disable_break(bool v) { break_disabled_ = v; }
 
   StackFrame::Id break_frame_id() { return thread_local_.break_frame_id_; }
   int break_id() { return thread_local_.break_id_; }
 
   // Support for embedding into generated code.
+  Address is_active_address() {
+    return reinterpret_cast<Address>(&is_active_);
+  }
+
   Address after_break_target_address() {
     return reinterpret_cast<Address>(&after_break_target_);
   }
 
   Address restarter_frame_function_pointer_address() {
     Object*** address = &thread_local_.restarter_frame_function_pointer_;
     return reinterpret_cast<Address>(address);
   }
 
   Address step_in_fp_addr() {
@@ skipping 247 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_