Only stop if the transition on this element ended

This way it doesn't end when some random element elsewhere on the page has an ending transition.

It must be noted that this is not a complete fix. If you have multiple transitions on the element, it still ends when the first ends.

I ran into this not working (the transition ends almost immediately, because some unrelated transition ends). This fixes it for me, but I was wondering whether this cornercase was considered, and whether the other cornercase (multiple transitions) was considered.

I think it's very hard to get this correct, and think it might be better to make the timeout explicit, or at least allow to set it explicit, and fall back to this behaviour. But I'm really interested in feedback on this one.
Guard against contentEditable with children props
Added event parameter
Make sure it works when we have no css transitions
Apply component and mixins specs deterministically
Fixes #1589.
add picture element and related attributes
add picture to xjs.knownTags
Add support for <dialog> tag.

fixes #2017
Throw an error when functions on `statics` clash due to duplicate keys
More informative error message for mergeObjectsWithNoDuplicateKeys
Abbreviated error message
Throw if a reserved property is defined in 'statics'
Deprecate 'return false' in event handlers
JSXTransformer respects async attribute

Conflicts:
	vendor/browser-transforms.js
Re-add  with warning and monitorCodeUse
Update recast to 0.6, update constants.js

I dropped the part of constants.js that we weren't using (namely the
part where we insert constants) but left it open to do that. It should
be trivial, we just aren't using it.

Fixes #1824
Merge pull request #2042 from zpao/update-recast

Update recast to 0.6, update constants.js
Merge pull request #1826 from syranide/jsxasync

JSXTransformer respects async attribute
Fixed style and comment nits
Test for both true and false