Style sheet parsing and test

New style sheet parsing.
To be evaluated.

Visual effect:

![image](https://cloud.githubusercontent.com/assets/1194048/3643669/36dffc74-10d7-11e4-8195-ac7b65f2565e.png)

I put back the old style getCssRules to avoid incompatibility with node.js that could not handle document.implementation.createHTMLdocument()....

Added test case that test both getCSSRule function and getglobalstyleforelement ( using parseAttributes , i cannot test that function directly )
Ok, if you can update now, I think it's good for merge!