Factor out NullExecutionContext from unittest files.

Source/core/testing/NullExecutionContext.cpp

Index: Source/core/testing/NullExecutionContext.cpp
diff --git a/Source/core/testing/NullExecutionContext.cpp b/Source/core/testing/NullExecutionContext.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..b0f18f82d3e2069bc71a475c4b86115f31181906
--- /dev/null
+++ b/Source/core/testing/NullExecutionContext.cpp
@@ -0,0 +1,30 @@
+// Copyright 2014 The Chromium 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 "config.h"
+
+#include "core/testing/NullExecutionContext.h"
+
+namespace WebCore {
+
+namespace {
+
+class NullEventQueue FINAL : public EventQueue {
+public:
+    NullEventQueue() { }
+    virtual ~NullEventQueue() { }
+    virtual bool enqueueEvent(PassRefPtrWillBeRawPtr<Event>) OVERRIDE { return true; }
+    virtual bool cancelEvent(Event*) OVERRIDE { return true; }
+    virtual void close() OVERRIDE { }
+};
+
+} // namespace
+
+NullExecutionContext::NullExecutionContext()
+    : m_tasksNeedSuspension(false)
+    , m_queue(adoptPtrWillBeNoop(new NullEventQueue()))
+{
+}
+
+} // namespace WebCore