Introduce intrinsic to expose debug state to generated code.

src/assembler.h

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // 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.
 //
@@ skipping 893 matching lines @@
 
   static ExternalReference math_exp_constants(int constant_index);
   static ExternalReference math_exp_log_table();
 
   static ExternalReference page_flags(Page* page);
 
   static ExternalReference ForDeoptEntry(Address entry);
 
   static ExternalReference cpu_features();
 
+  static ExternalReference debug_is_active_address(Isolate* isolate);
   static ExternalReference debug_after_break_target_address(Isolate* isolate);
   static ExternalReference debug_restarter_frame_function_pointer_address(
       Isolate* isolate);
 
   static ExternalReference is_profiling_address(Isolate* isolate);
   static ExternalReference invoke_function_callback(Isolate* isolate);
   static ExternalReference invoke_accessor_getter_callback(Isolate* isolate);
 
   Address address() const { return reinterpret_cast<Address>(address_); }
 
@@ skipping 225 matching lines @@
 
  private:
   int32_t multiplier_;
   int32_t shift_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_ASSEMBLER_H_