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      <base href="https://bugs.webkit.org/" />
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    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - The animation is running in the background without stop."
   href="https://bugs.webkit.org/show_bug.cgi?id=146451">146451</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>The animation is running in the background without stop.
          </td>
        </tr>

        <tr>
          <th>Classification</th>
          <td>Unclassified
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>WebKit
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>528+ (Nightly build)
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>Unspecified
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>Unspecified
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>Normal
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>P2
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>Animations
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>webkit-unassigned&#64;lists.webkit.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>mwang&#64;opentv.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>dino&#64;apple.com
          </td>
        </tr></table>
      <p>
        <div>
        <pre>This issue happens only if accelerated-compositing is enabled.

The attached simple test case is to load an iframe with 'display:none', which has some animations. Although nothing is displayed when it is loaded, 50% CPU is consumed (depends on different platform).  

If adding a log in ImplicitAnimation::timeToNextService() of ImplicitAnimation.cpp
double ImplicitAnimation::timeToNextService()
{
    printf(&quot;[LOG]ImplicitAnimation::timeToNextService(%p)\n&quot;, this);
    double t = AnimationBase::timeToNextService();
    ......
}

Lots of logs were outputted in the console, like 
    [LOG]ImplicitAnimation::timeToNextService(0x726e9ec8)
    [LOG]ImplicitAnimation::timeToNextService(0x726e9e70)
    [LOG]ImplicitAnimation::timeToNextService(0x726e9000)
    [LOG]ImplicitAnimation::timeToNextService(0x726e9058)
    [LOG]ImplicitAnimation::timeToNextService(0x726e9ec8)
    [LOG]ImplicitAnimation::timeToNextService(0x726e9e70)
    [LOG]ImplicitAnimation::timeToNextService(0x726e9f78)
    [LOG]ImplicitAnimation::timeToNextService(0x726e9f20)
    [LOG]ImplicitAnimation::timeToNextService(0x726e9058)
    [LOG]ImplicitAnimation::timeToNextService(0x726e9000)

How to reproduce this issue?
1/ unzip simple_case.zip
2/ enable accelerated-compositing
3/ load unzipped tbc.html 

The reason is in GraphicsLayerTextureMapper::addAnimation(). 
This issue is the side-effect of replacing m_animationStartedTimer.startOneShot(0) by notifyChange(AnimationStarted) in GraphicsLayerTextureMapper::addAnimation(). In fact, if the current GraphicsLayerTextureMapper object is not in GraphicsLayer tree, like the iframe in the attached simple case, it's GraphicsLayerTextureMapper::commitLayerChanges() can't be triggered, so AnimationStarted event can't be dispatched into AnimationController to stop the animation timer.</pre>
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