autocomplete in webui pages: Construct a new event instead of reusing an old one

BUG=109341
TEST=use arrow keys on list of autocomplete suggestions on settings page

Review URL: http://codereview.chromium.org/9116034

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@117047 0039d316-1c4b-4281-b951-d872f2087c98
2 files changed