Based on feedback from Glenn Maynard, the WebGL spec was just updated to avoid side-effects of registering event handlers. Now, in order for webglcontextrestored to be delivered to the application, the developer must have registered a webglcontextlost handler, and that handler needs to call preventDefault() against the event object. WebKit's WebGL implementation needs to be updated to track this change, and ideally layout tests written using the WEBKIT_lose_context extension either created or updated.
Created attachment 101556 [details] Patch
Comment on attachment 101556 [details] Patch OK
Committed r91504: <http://trac.webkit.org/changeset/91504>