Do not reverse lookup code stubs dictionary.

src/debug.cc

 // 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.
 
 #include "src/v8.h"
 
 #include "src/api.h"
 #include "src/arguments.h"
 #include "src/bootstrapper.h"
 #include "src/code-stubs.h"
@@ skipping 1471 matching lines @@
     if (is_at_restarted_function) {
       Handle<JSFunction> restarted_function(
           JSFunction::cast(*thread_local_.restarter_frame_function_pointer_));
       FloodWithOneShot(restarted_function);
     } else if (!call_function_stub.is_null()) {
       // If it's CallFunction stub ensure target function is compiled and flood
       // it with one shot breakpoints.
       bool is_call_ic = call_function_stub->kind() == Code::CALL_IC;
 
       // 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(
-          isolate_->heap()->code_stubs()->SlowReverseLookup(
-              *call_function_stub),
-          isolate_);
-      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();
+      uint32_t key = call_function_stub->stub_key();
       // Argc in the stub is the number of arguments passed - not the
       // expected arguments of the called function.
       int call_function_arg_count = is_call_ic
           ? CallICStub::ExtractArgcFromMinorKey(CodeStub::MinorKeyFromKey(key))
           : CallFunctionStub::ExtractArgcFromMinorKey(
               CodeStub::MinorKeyFromKey(key));
 
       ASSERT(is_call_ic ||
              CodeStub::GetMajorKey(*call_function_stub) ==
                  CodeStub::MajorKeyFromKey(key));
@@ skipping 1894 matching lines @@
   logger_->DebugEvent("Put", message.text());
 }
 
 
 void LockingCommandMessageQueue::Clear() {
   base::LockGuard<base::Mutex> lock_guard(&mutex_);
   queue_.Clear();
 }
 
 } }  // namespace v8::internal