Reviewed by Oliver.

Reviewed by Oliver.

Fixes: http://bugs.webkit.org/show_bug.cgi?id=17779 (SVG 1.1 Errata demands "SVG JavaScript Liveness" support)
SVG Errata states: "All SVG DOM objects that directly correspond to an
attribute, e.g. the SVGAnimatedLength 'ry' in an SVGRectElement, are live. This
means that any changes made to the attribute are immediately reflected in the
corresponding SVG DOM object." (see linked URL on bug report)

Until now only XML -> SVG DOM changes took affect, aka. changing the 'rx' attribute of a <rect>
element resuted in changes when accessing 'rx' through SVG DOM (rx.baseVal.value).

Add a new synchronization layer to handle SVG DOM -> XML changes.

Added Test: svg/custom/svg-xml-dom-sync.html

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@31566 268f45cc-cd09-0410-ab3c-d52691b4dbfc