Fix a browser crasher with negative index set on select popups.
Fix a browser crasher with negative index set on select popups.

BUG=63774
TEST=Visit http://vescam.com/select_crasher.html and try all the selects
     in that page.

Review URL: http://codereview.chromium.org/5302009

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@67969 0039d316-1c4b-4281-b951-d872f2087c98

adobe/chromium,gavinp/chromium,Crystalnix/house-of-life-chromium,ropik/chromium,adobe/chromium,ropik/chromium,yitian134/chromium,Crystalnix/house-of-life-chromium,yitian134/chromium,yitian134/chromium,Crystalnix/house-of-life-chromium,gavinp/chromium,ropik/chromium,yitian134/chromium,ropik/chromium,Crystalnix/house-of-life-chromium,yitian134/chromium,Crystalnix/house-of-life-chromium,adobe/chromium,ropik/chromium,gavinp/chromium,adobe/chromium,adobe/chromium,Crystalnix/house-of-life-chromium,yitian134/chromium,adobe/chromium,gavinp/chromium,adobe/chromium,ropik/chromium,gavinp/chromium,Crystalnix/house-of-life-chromium,gavinp/chromium,yitian134/chromium,Crystalnix/house-of-life-chromium,Crystalnix/house-of-life-chromium,Crystalnix/house-of-life-chromium,gavinp/chromium,yitian134/chromium,adobe/chromium,gavinp/chromium,gavinp/chromium,ropik/chromium,yitian134/chromium,adobe/chromium,adobe/chromium,ropik/chromium,Crystalnix/house-of-life-chromium,yitian134/chromium,gavinp/chromium,adobe/chromium,ropik/chromium