Use proportional line height for menu items to prevent clipping.

BUG=305913

Review URL: https://codereview.chromium.org/75963006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@236421 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 236421