Fix |RunMicrotasks()| leaking reference to the last context being run on.

src/execution.cc

 // Copyright 2014 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 "execution.h"
 
 #include "bootstrapper.h"
 #include "codegen.h"
 #include "deoptimizer.h"
 #include "isolate-inl.h"
@@ skipping 306 matching lines @@
       isolate->factory()->undefined_value(),
       0,
       NULL).Assert();
 }
 
 
 void Execution::EnqueueMicrotask(Isolate* isolate, Handle<Object> microtask) {
   Handle<Object> args[] = { microtask };
   Execution::Call(
       isolate,
-      isolate->enqueue_external_microtask(),
+      isolate->enqueue_microtask(),
       isolate->factory()->undefined_value(),
       1,
       args).Assert();
 }
 
 
 bool StackGuard::IsStackOverflow() {
   ExecutionAccess access(isolate_);
   return (thread_local_.jslimit_ != kInterruptLimit &&
           thread_local_.climit_ != kInterruptLimit);
@@ skipping 647 matching lines @@
   if (stack_guard->IsInstallCodeRequest()) {
     ASSERT(isolate->concurrent_recompilation_enabled());
     stack_guard->Continue(INSTALL_CODE);
     isolate->optimizing_compiler_thread()->InstallOptimizedFunctions();
   }
   isolate->runtime_profiler()->OptimizeNow();
   return isolate->heap()->undefined_value();
 }
 
 } }  // namespace v8::internal