[dom] Fix a bug with setStyle() cannot set an opacity to 1 (fix #1469)

This problem occurs when you try to set an opacity to 1 using `node.setStyle()` method on IE. It has adapted to change an opacity only if less than 1, but we should change an opacity, even if it passed 1. Fix #1469.

Tested with IE6, IE7, IE8, IE9, IE10, Chrome (stable), Firefox (stable), Safari 7.0, Safari (iOS7).

```
[okuryu.local](yui3@fix1469)$ yeti tests/unit/dom.html
  Agent connected: Internet Explorer (6.0) / Windows XP from 10.0.1.6
  Agent connected: Chrome (31.0.1650.63) / Mac OS from 127.0.0.1
  Agent connected: Firefox (26.0) / Mac OS from 127.0.0.1
  Agent connected: Internet Explorer (7.0) / Windows XP from 10.0.1.6
  Agent connected: Safari (7.0) / Mac OS from 127.0.0.1
  Agent connected: Internet Explorer (8.0) / Windows 7 from 10.0.1.6
  Agent connected: Internet Explorer (9.0) / Windows 7 from 10.0.1.6
  Agent connected: Internet Explorer (10.0) / Windows 7 from 10.0.1.6
  Agent connected: Safari (7.0) / iOS 7.0.4 from 10.0.1.12
✓ Testing started on Internet Explorer (6.0) / Windows XP, Chrome (31.0.1650.63) / Mac OS, Firefox (26.0) / Mac OS, Internet Explorer (7.0) / Windows XP, Safari (7.0) / Mac OS, Internet Explorer (8.0) / Windows 7, Internet Explorer (9.0) / Windows 7, Internet Explorer (10.0) / Windows 7, Safari (7.0) / iOS 7.0.4
✓ Agent completed: Internet Explorer (10.0) / Windows 7
✓ Agent completed: Internet Explorer (9.0) / Windows 7
✓ Agent completed: Safari (7.0) / iOS 7.0.4
✓ Agent completed: Safari (7.0) / Mac OS
✓ Agent completed: Firefox (26.0) / Mac OS
✓ Agent completed: Internet Explorer (8.0) / Windows 7
✓ Agent completed: Internet Explorer (6.0) / Windows XP
✓ Agent completed: Internet Explorer (7.0) / Windows XP
✓ Agent completed: Chrome (31.0.1650.63) / Mac OS
✓ 189 tests passed! (25 seconds)
```