Add onanimationXXX attributes on HTML elements.

Add onanimationXXX attributes on HTML elements.

Add onanimationXXX attributes on HTML elements to match the prefixed
attributes onwebkitanimationXXX. As it uses the same plumbing as a
regular event listeners, it behaves the same which means that if
onanimationXXX only is defined then only the code attached to this
attribute will be called, if only onwebkitanimationXXX is defined then
only the code attached to this attribute will be called and finally if
both attributes are defined then only the code attached to the
unprefixed attribute will be called.

BUG=234611
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=157121

[dstockwell, 2013-09-03 09:34:18]

lgtm

[commit-bot: I haz the power, 2013-09-03 11:15:51]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/alexis.menard@intel.com/23583032/1

[commit-bot: I haz the power, 2013-09-03 11:20:47]

Change committed as 157121