Order of actions for labeled control should be focus then click.

When we click on a checkbox or a radio button, event order is:
 - mousedown
 - focus, triggered by mousedown
 - mouseup
 - change, triggered by the following click <wkbug.com/93674>
 - click

That is to say, we focus on it first and then click it. Click on an
associated label should have same behavior.

BUG=264567

Review URL: https://chromiumcodereview.appspot.com/21005002

git-svn-id: svn://svn.chromium.org/blink/trunk@155162 bbb929c8-8fbe-4397-9dbb-9b2b20218538