Rename IdleCallbackDeadline to IdleDeadline to be in sync with spec.

Source/core/dom/IdleCallbackDeadline.h

-// Copyright 2015 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.
-
-#ifndef IdleCallbackDeadline_h
-#define IdleCallbackDeadline_h
-
-#include "bindings/core/v8/ScriptWrappable.h"
-#include "platform/heap/Handle.h"
-
-namespace blink {
-
-class IdleCallbackDeadline : public GarbageCollected<IdleCallbackDeadline>, public ScriptWrappable {
-    DEFINE_WRAPPERTYPEINFO();
-public:
-    enum class CallbackType {
-        CalledWhenIdle,
-        CalledByTimeout
-    };
-
-    static IdleCallbackDeadline* create(double deadlineSeconds, CallbackType callbackType)
-    {
-        return new IdleCallbackDeadline(deadlineSeconds, callbackType);
-    }
-
-    DEFINE_INLINE_TRACE() { }
-
-    double timeRemaining() const;
-
-    bool didTimeout() const
-    {
-        return m_callbackType == CallbackType::CalledByTimeout;
-    }
-
-private:
-    IdleCallbackDeadline(double deadlineSeconds, CallbackType);
-
-    double m_deadlineSeconds;
-    CallbackType m_callbackType;
-};
-
-} // namespace blink
-
-#endif // IdleCallbackDeadline_h