Add mechanism to handle [CEReactions] extended IDL attributes

[pmdartus]

Custom elements lifecycle hooks invocation depend on [CEReactions] extended IDL attributes. The CSSStyleDeclaration interface has multiple occurrences of this extended attribute:

• cssText
• setProperty
• removeProperty
• cssFloat
• all the camel case, dashed case and webkit cases properties.

Adding support for such hooks would allow jsdom to invoke the attributeChangedCallback whenever the style attribute changes.

[ExE-Boss]

This will be possible once #116 is implemented.