Autofill/rAc: dispatch "input"/"change" on <input>, <textarea>, and <select>

      elements when autofilled.

This more closely matches the spec behavior[1]:

"""
When the user agent is to change an input element's value on behalf of the user
(e.g. as part of a form prefilling feature), the user agent must queue a task to
first update the value accordingly, then fire a simple event that bubbles named
input at the input element, then fire a simple event that bubbles named change
at the input element.
"""

BUG=353691,354257
R=isherman@chromium.org

[1] http://www.whatwg.org/specs/web-apps/current-work/multipage/common-input-element-attributes.html#event-input-input

Review URL: https://codereview.chromium.org/214823011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@260474 0039d316-1c4b-4281-b951-d872f2087c98