In the process, the BASE element and related functions are only implemented if that support is true, and BASE urls now use a full URL path when set, to avoid issues with browsers that may need that.
Fixes#263, Fixes#221
- boxShadow (tests that the property is defined and window.blackberry is false, as BB's shadows have no feathering)
- scrollTop (tests that the property is defined and that a webos property or two isn't defined, as Palm always reports 0)
Added an existence test for CSS properties, which is used for cssPseudoElement and boxShadow).