yui/yui3 — pull request #1162 by derek (2013-09-04 21:57:18+00:00)
Title: Added HTML support for Button labels 

Currently [`Y.Button`](http://yuilibrary.com/yui/docs/button/) widgets do not support HTML labels. This is an issue because is isn't uncommon to use nested HTML structures inside of a `` element. For example...

```

I Am A

Button

Image Button

```

To fix this issue, this pull request introduces a `labelHTML` ATTR, and relegates the `label` ATTR as secure sugar around `labelHTML`.

A separate attribute is required for the following reasons:
1. To not introduce security vulnerabilities to existing implementations who use the `label` ATTR
2. To convey the insecurity of this attribute by including "HTML" in the name

**Additional notes**
* Using `@config` instead of `@attribute` in ButtonCore documentation because `@attribute` will include the `Change` events to the API documentation, which ButtonCore (derived from AttributeCore) does not fire.
* Fixed unrelated breakage in Selleck tests

**Test Results**

✓ Agent completed: Internet Explorer (9.0) / Windows 7
✓ Agent completed: Chrome (29.0.1547.65) / Mac OS
✓ Agent completed: Safari (6.0.5) / Mac OS
✓ Agent completed: Internet Explorer (10.0) / Windows 8
✓ Agent completed: Internet Explorer (8.0) / Windows XP
✓ Agent completed: Internet Explorer (6.0) / Windows XP
✓ Agent completed: Internet Explorer (7.0) / Windows XP
✓ Agent completed: Firefox (23.0) / Mac OS
✓ Agent completed: Safari (4.0) / Linux (Android 2.3.4)
✓ Agent completed: Safari (4.0) / Linux (Android 3.0.1)

✓ 352 tests passed! (1 minutes, 2 seconds)