mouse move events. This prevents an HTML widget from staying in the mouseover 
state when the cursor leaves the window. Add a new ui test that checks 
the specific case that was broken by warping the mouse pointer inside and 
outside the content area. 

BUG=24660
TEST=ui_tests 

patch by Dominic Mazzoni <dmazzoni [at] google>
original review: http://codereview.chromium.org/274010/show

Review URL: http://codereview.chromium.org/354010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@30726 0039d316-1c4b-4281-b951-d872f2087c98