Clean up KeyframeValueList and related classes
https://bugs.webkit.org/show_bug.cgi?id=115738

Reviewed by Simon Fraser.

Source/WebCore:

Add static create() functions to the AnimationValue subclasses, and change a bunch of parameters
and return values that can never be null from pointer types to reference types to better indicate this.

* platform/graphics/GraphicsLayer.cpp:
(WebCore::filterOperationsAt):
(WebCore::GraphicsLayer::validateFilterOperations):
(WebCore::operationsAt):
(WebCore::GraphicsLayer::validateTransformOperations):
* platform/graphics/GraphicsLayer.h:
(AnimationValue):
(WebCore::AnimationValue::AnimationValue):
(WebCore::FloatAnimationValue::create):
(FloatAnimationValue):
(WebCore::FloatAnimationValue::FloatAnimationValue):
(WebCore::TransformAnimationValue::create):
(TransformAnimationValue):
(WebCore::TransformAnimationValue::value):
(WebCore::TransformAnimationValue::TransformAnimationValue):
(WebCore::FilterAnimationValue::create):
(WebCore::FilterAnimationValue::value):
(WebCore::FilterAnimationValue::FilterAnimationValue):
(FilterAnimationValue):
(WebCore::KeyframeValueList::~KeyframeValueList):
(KeyframeValueList):
(WebCore::KeyframeValueList::at):
* platform/graphics/ca/GraphicsLayerCA.cpp:
(WebCore::animationHasStepsTimingFunction):
(WebCore::GraphicsLayerCA::createTransformAnimationsFromKeyframes):
(WebCore::GraphicsLayerCA::createFilterAnimationsFromKeyframes):
(WebCore::GraphicsLayerCA::timingFunctionForAnimationValue):
(WebCore::GraphicsLayerCA::setAnimationEndpoints):
(WebCore::GraphicsLayerCA::setAnimationKeyframes):
(WebCore::GraphicsLayerCA::setTransformAnimationEndpoints):
(WebCore::GraphicsLayerCA::setTransformAnimationKeyframes):
(WebCore::GraphicsLayerCA::setFilterAnimationEndpoints):
(WebCore::GraphicsLayerCA::setFilterAnimationKeyframes):
* platform/graphics/ca/GraphicsLayerCA.h:
(GraphicsLayerCA):
* rendering/RenderLayerBacking.cpp:
(WebCore::RenderLayerBacking::startAnimation):
(WebCore::RenderLayerBacking::startTransition):

Source/WebKit2:

Update for WebCore changes.

* Shared/CoordinatedGraphics/CoordinatedGraphicsArgumentCoders.cpp:
(CoreIPC::::decode):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@149694 268f45cc-cd09-0410-ab3c-d52691b4dbfc