[WK2][Qt] REGRESSION: Pages with transform animations sometimes omit some of the...

[WK2][Qt] REGRESSION: Pages with transform animations sometimes omit some of the layers since r105413
https://bugs.webkit.org/show_bug.cgi?id=76886

Reviewed by Kenneth Rohde Christiansen.

We now render the whole layer if it or one if its ancestors has an active transform
animations. It's possible to optimize further in the future, but not currently necessary.
Also, we make sure that when a WebGraphicsLayer's property that affects transformation is
changed, all its descandants layers are marked as modified so that we re-adjust their
visible rect in the next pass.

* WebProcess/WebCoreSupport/WebGraphicsLayer.cpp:
(WebCore::WebGraphicsLayer::notifyChangeRecursively):
(WebCore):
(WebCore::WebGraphicsLayer::setPosition):
(WebCore::WebGraphicsLayer::setAnchorPoint):
(WebCore::WebGraphicsLayer::setSize):
(WebCore::WebGraphicsLayer::setTransform):
(WebCore::WebGraphicsLayer::setChildrenTransform):
(WebCore::WebGraphicsLayer::setPreserves3D):
(WebCore::WebGraphicsLayer::setMasksToBounds):
(WebCore::WebGraphicsLayer::addAnimation):
(WebCore::WebGraphicsLayer::removeAnimation):
(WebCore::WebGraphicsLayer::tiledBackingStoreVisibleRect):
(WebCore::WebGraphicsLayer::selfOrAncestorHasActiveTransformAnimations):
* WebProcess/WebCoreSupport/WebGraphicsLayer.h:
(WebGraphicsLayer):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@105934 268f45cc-cd09-0410-ab3c-d52691b4dbfc