Unify SVG's animation and target tracking systems.

Unify SVG's animation and target tracking systems.
https://bugs.webkit.org/show_bug.cgi?id=102655

Reviewed by Dirk Schulze.

Source/WebCore:

This patch unifies our animation target tracking system and regular target tracking system.
This simplifies the code, fixes a bug, and cleans up a historically security-sensitive area.

Background: When <use>, <mpath>, <animate>, etc. reference another element using
xlink:href="#id", we need to track when #id changes to #otherId, when #id is removed, etc.
This bookkeeping of element -> target is done in SVGDocumentExtensions. Additionally, when
a target changes that causes layout (e.g., rect.x is changed), all dependent elements with
renderers are notified (<animate> has no renderer and will not use this).

Previously, xlink:href changes were lazily resolved when targetElement() was called, target
changes were tracked using the animation tracking framework, and pending targets did not
work (e.g., <animate xlink:href="#p"><!--animate is now pending #p --><rect id="p"/>).

After this patch, we no longer lazily resolve targetElement() but instead change it when
our xlink:href attribute changes. Instead of using the animation tracking framework in
SVGDocumentExtensions, we now use the regular target tracking framework. Lastly, by using
the regular target tracking framework we are able to hook into the pending resource handling
which fixes a bug (see the test).

A test has been added to test that the order of animation elements does not matter. A second
test has been added to show we do not regress a pending-while-pending case.

Tests: svg/animations/svg-animation-order.html
       svg/custom/svg-pending-twice.html

* svg/SVGAnimateElement.cpp:
(WebCore::SVGAnimateElement::setTargetElement):

    setTargetElement and setAttributeName now work similarly. When the corresponding attribute
    changes, we update our internal state (target or attributeName) and save it instead of
    looking these values up on each iteration.

(WebCore::SVGAnimateElement::setAttributeName):
(WebCore):
(WebCore::SVGAnimateElement::resetAnimatedPropertyType):
* svg/SVGAnimateElement.h:
(SVGAnimateElement):
* svg/SVGAnimationElement.cpp:
(WebCore::SVGAnimationElement::setAttributeType):
(WebCore::SVGAnimationElement::setTargetElement):
(WebCore::SVGAnimationElement::setAttributeName):
* svg/SVGAnimationElement.h:
(SVGAnimationElement):
* svg/SVGDocumentExtensions.cpp:
(WebCore::SVGDocumentExtensions::~SVGDocumentExtensions):
(WebCore):
* svg/SVGDocumentExtensions.h:
(SVGDocumentExtensions):
* svg/SVGElement.cpp:
(WebCore::SVGElement::~SVGElement):
(WebCore::SVGElement::removedFrom):
(WebCore::SVGElement::attributeChanged):
* svg/SVGElementInstance.cpp:
(WebCore::SVGElementInstance::invalidateAllInstancesOfElement):

    This can be removed after r131631 landed.

* svg/SVGMPathElement.cpp:
(WebCore::SVGMPathElement::buildPendingResource):
* svg/SVGTextPathElement.cpp:
(WebCore::SVGTextPathElement::buildPendingResource):

    A bug was discovered in review with our resource tracking in a pending-while-pending
    case. SVGMpathElement and SVGTextPathElement have been updated to fix this as well.

* svg/animation/SVGSMILElement.cpp:

    The changes in SVGSMILElement should look very similar to SVGFEImageElement,
    SVGMPathElement, etc. The idea is to build pending resources when added or
    removed from the document, or when the href attribute changes.

(WebCore::SVGSMILElement::~SVGSMILElement):
(WebCore):
(WebCore::SVGSMILElement::clearResourceReferences):
(WebCore::SVGSMILElement::buildPendingResource):
(WebCore::SVGSMILElement::insertedInto):
(WebCore::SVGSMILElement::removedFrom):
(WebCore::SVGSMILElement::svgAttributeChanged):
(WebCore::SVGSMILElement::setAttributeName):
(WebCore::SVGSMILElement::setTargetElement):
* svg/animation/SVGSMILElement.h:
(WebCore):
(WebCore::SVGSMILElement::targetElement):
(SVGSMILElement):

LayoutTests:

* svg/animations/svg-animation-order-expected.html: Added.
* svg/animations/svg-animation-order.html: Added.
* svg/custom/svg-pending-twice-expected.html: Added.
* svg/custom/svg-pending-twice.html: Added.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@136906 268f45cc-cd09-0410-ab3c-d52691b4dbfc