Introduce CSS Shapes Parsing Tests for Basic Shapes

This set of tests focuses on the sections defining the shape-outside property and the basic shapes.
The tests make sure different variations of the basic shapes are parsed correctly, and that getComputedStyle contains the used style.

The sections of the spec are:
http://dev.w3.org/csswg/css-shapes/#basic-shapes-from-svg-syntax 
http://dev.w3.org/csswg/css-shapes/#shape-outside-property