Attempt to fix GCMole warning.

src/bootstrapper.cc

 // Copyright 2011 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 1922 matching lines @@
     return false;
   }
   ASSERT(current->state() == v8::UNVISITED);
   current->set_state(v8::VISITED);
   v8::Extension* extension = current->extension();
   // Install the extension's dependencies
   for (int i = 0; i < extension->dependency_count(); i++) {
     if (!InstallExtension(extension->dependencies()[i])) return false;
   }
   Isolate* isolate = Isolate::Current();
+  Handle<String> source_code =
+      isolate->factory()->NewExternalStringFromAscii(extension->source());
   bool result = CompileScriptCached(
       CStrVector(extension->name()),
-      isolate->factory()->NewExternalStringFromAscii(extension->source()),
+      source_code,
       isolate->bootstrapper()->extensions_cache(),
       extension,
       Handle<Context>(isolate->context()),
       false);
   ASSERT(isolate->has_pending_exception() != result);
   if (!result) {
     isolate->clear_pending_exception();
   }
   current->set_state(v8::INSTALLED);
   return result;
@@ skipping 270 matching lines @@
   return from + sizeof(NestingCounterType);
 }
 
 
 // Called when the top-level V8 mutex is destroyed.
 void Bootstrapper::FreeThreadResources() {
   ASSERT(!IsActive());
 }
 
 } }  // namespace v8::internal