Enable the SVG GlobalEventHandlers test

I forgot this in a previous commit. It turns out that SVGSVGElement
forwards some of these properties to window, which broke the tests,
so use a SVGRectElement for testing instead.

BUG=305112

Review URL: https://codereview.chromium.org/26599003

git-svn-id: svn://svn.chromium.org/blink/trunk@159689 bbb929c8-8fbe-4397-9dbb-9b2b20218538