Remove 'begin'/'end' processing from SVGSMILElement::svgAttributeChanged

The svgAttributeChanged hook is (with one exception) used for attributes
that are part of the SVG DOM representation ("object model".) 'begin'
and 'end' are not. Move handling to SVGSMILElement::parseAttribute
instead.

BUG=641437

Review-Url: https://codereview.chromium.org/2719493002
Cr-Commit-Position: refs/heads/master@{#452858}
1 file changed