Work around chrome caret bug.

Fixes #175.

I've tested on all the IEs, Firefoxes and Chromes five versions back, Safari 5.1/6/7, iOS 4/5.1/6/7/8, Android 1.6/2.3/4.1/4.4, Opera mobile.

The only issue I saw was on Android 1.6, in which when the input box was selected the font was slightly bigger than the text field. That happened regardless of this change, however.