Reviewed by Anders Carlsson.

        Accelerated animations stutter on pages with lots of animations and 3d transforms
        https://bugs.webkit.org/show_bug.cgi?id=27884

        This patch changes the strategy for synchronizing painting view the view,
        and compositing layer updates. Previously the strategy was to disable screen
        updates between the time we updated the layer tree, and painted the view. That
        left screen updates disabled for too long (hundreds of milliseconds) in some
        cases, causing animation stutter.

        The new strategy is to batch up changes to the CA layer tree, and commit them
        all at once just before painting happens (referred to as a "sync" in the code).
        GraphicsLayerCA now keeps a bitmask of changed properties, and then migrates
        the values stored in GraphicsLayer into the CA layer tree at commit time.

        Compositing layers are then synced in FrameView::paintContents(). However, not
        all style/layout changes will result in painting; to deal with style changes that
        touch only compositing properties, we set up a runloop observer that takes care
        of comitting layer changes when no painting happens.

        * WebCore.base.exp: Export FrameView::syncCompositingStateRecursive()

        * loader/EmptyClients.h: scheduleViewUpdate() renamed to syncCompositingStateRecursive()
        * page/ChromeClient.h: scheduleViewUpdate() renamed to syncCompositingStateRecursive()

        * page/FrameView.h:
        * page/FrameView.cpp:
        (WebCore::FrameView::syncCompositingStateRecursive): syncCompositingState() on the
        view and all subviews. Like layoutIfNeededRecursive(). If layout is pending, does not
        sync and returns false, since we only want to sync when layout is done.

        (WebCore::FrameView::paintContents): syncCompositingState() before painting.

        * page/animation/KeyframeAnimation.cpp:
        (WebCore::KeyframeAnimation::endAnimation):
        Call animationPaused() to notify the graphics layers about animation pausing.

        * platform/graphics/FloatPoint3D.h:
        (WebCore::operator==):
        (WebCore::operator!=):
        Add missing comparison operators.

        * platform/graphics/GraphicsLayer.cpp:
        (WebCore::GraphicsLayer::setOpacity):
        (WebCore::GraphicsLayer::setBackgroundColor): Simple setters no longer care about animation info.

        (WebCore::GraphicsLayer::paintGraphicsLayerContents): Null-check client.

        * platform/graphics/GraphicsLayer.h:
        (WebCore::AnimationValue:):
        (WebCore::TransformAnimationValue:):
        (WebCore::KeyframeValueList:):
        (WebCore::KeyframeValueList::insert):
        Cleaned up versions of FloatValue and TransformValue, used to store information
        about keyframes values.

        (WebCore::GraphicsLayer::contentsRect):
        (WebCore::GraphicsLayer::setContentsRect):
        ContentsRect is now a simple setter.

        (WebCore::GraphicsLayer::addAnimation):
        (WebCore::GraphicsLayer::removeAnimationsForProperty):
        (WebCore::GraphicsLayer::removeAnimationsForKeyframes):
        (WebCore::GraphicsLayer::pauseAnimation):
        Simplified animation api.

        (WebCore::GraphicsLayer::setGeometryOrientation):
        (WebCore::GraphicsLayer::geometryOrientation):
        setGeometryOrientation is now just a normal member variable.

        (WebCore::GraphicsLayer::contentsOrientation): add a getter.
        (WebCore::GraphicsLayer::syncCompositingState): Entry into the layer sync code.

        * platform/graphics/GraphicsLayerClient.h: scheduleViewUpdate() renamed to syncCompositingStateRecursive)

        * platform/graphics/mac/GraphicsLayerCA.h:
        * platform/graphics/mac/GraphicsLayerCA.mm:
        Lots of cleanup and refactoring. Main points:
        - Layer changes are all batched, and only committed to the CA layer on syncCompositingState().
        - Bitmask is used to store which properties have changed. More efficient than before.
        - Simpler animation interface; simple setters are no longer confounded with animations.
        - Refactored code that creates CA animations, and stores which animations are running.

        * platform/graphics/transforms/TransformOperations.h:
        (WebCore::TransformOperations::size):
        (WebCore::TransformOperations::at): Useful accessors for size and indexed access.

        * rendering/RenderLayerBacking.h:
        * rendering/RenderLayerBacking.cpp:
        Renamed 'contentsLayer' to 'foregroundLayer' to avoid confusion with GraphicsLayer's
        contentsLayer.
        Adapt to GraphicsLayer's simpler animation API.
        Pass animation pausing through to the graphics layers.
        contentsBox() is no longer a callback via GraphicsLayerClient.

        * rendering/RenderLayerCompositor.h:
        * rendering/RenderLayerCompositor.cpp:
        (WebCore::RenderLayerCompositor::setCompositingLayersNeedRebuild):
        (WebCore::RenderLayerCompositor::scheduleSync):
        (WebCore::RenderLayerCompositor::rebuildCompositingLayerTree):
        scheduleViewUpdate() is no longer required. Instead, we plumb through "compositingLayerSync"
        notifications, which travel up to WebKit and set up a runloop observer.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@46645 268f45cc-cd09-0410-ab3c-d52691b4dbfc