[Isolates] Avoid dereferencing Isolate::Current() to check oddball identities...

src/debug.cc

 // Copyright 2006-2008 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 1039 matching lines @@
   };
   Handle<Object> result = Execution::TryCall(check_break_point,
       Isolate::Current()->js_builtins_object(), argc, argv, &caught_exception);
 
   // If exception or non boolean result handle as not triggered
   if (caught_exception || !result->IsBoolean()) {
     return false;
   }
 
   // Return whether the break point is triggered.
-  return *result == HEAP->true_value();
+  ASSERT(!result.is_null());
+  return (*result)->IsTrue();
 }
 
 
 // Check whether the function has debug information.
 bool Debug::HasDebugInfo(Handle<SharedFunctionInfo> shared) {
   return !shared->debug_info()->IsUndefined();
 }
 
 
 // Return the debug info for this function. EnsureDebugInfo must be called
@@ skipping 255 matching lines @@
     thread_local_.last_fp_ = frame->fp();
   } else {
     // If it's CallFunction stub ensure target function is compiled and flood
     // it with one shot breakpoints.
     if (!call_function_stub.is_null()) {
       // Find out number of arguments from the stub minor key.
       // Reverse lookup required as the minor key cannot be retrieved
       // from the code object.
       Handle<Object> obj(
           HEAP->code_stubs()->SlowReverseLookup(*call_function_stub));
-      ASSERT(*obj != HEAP->undefined_value());
+      ASSERT(!obj.is_null());
+      ASSERT(!(*obj)->IsUndefined());
       ASSERT(obj->IsSmi());
       // Get the STUB key and extract major and minor key.
       uint32_t key = Smi::cast(*obj)->value();
       // Argc in the stub is the number of arguments passed - not the
       // expected arguments of the called function.
       int call_function_arg_count =
           CallFunctionStub::ExtractArgcFromMinorKey(
               CodeStub::MinorKeyFromKey(key));
       ASSERT(call_function_stub->major_key() ==
              CodeStub::MajorKeyFromKey(key));
@@ skipping 1735 matching lines @@
     {
       Locker locker;
       Isolate::Current()->debugger()->CallMessageDispatchHandler();
     }
   }
 }
 
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 } }  // namespace v8::internal