Add basic support for touch events.

* Whitelist touch event types (touchstart, etc.)
* Tame event properties touches, targetTouches, changedTouches.
* Tamings for Touch and TouchList types.

Supporting changes:
* PT.TameMemoIf now uses the property name from the environment
  (refactoring only).
* Removed stray whitespace in domado.js.

Note that there are unfortunately no tests added since the existing
test automation only does click events (not touches) and there does not
appear to be a portable way to create touch events or other
touch-related data types from within the browser, even.

@r5644, r5645

[felix8a, 2013-12-10 23:41:54]

lgtm modulo typo

I'm ok with the flimsy testing, but it might be nice to have a manual demo app
somewhere, which would probably have caught the typo.

https://codereview.appspot.com/40570044/diff/1/src/com/google/caja/plugin/dom...
File src/com/google/caja/plugin/domado.js (right):

https://codereview.appspot.com/40570044/diff/1/src/com/google/caja/plugin/dom...
src/com/google/caja/plugin/domado.js:5935: this.target =
tameRelatedNode(feral.taeget);
typo "taeget"