Scrawl-canvas v8 - Filters test 501

Test purpose

• Create a test Picture entity, and a Phrase entity
• Apply a set of CSS-based filter Strings to the entitys, and to the Cell
• Check that the selected entity/Cell updates its display in line with the current filter String

Known issue: Webkit-based browsers (for instance, Safari) have not yet implemented the Canvas context 'filter' attribute functionality.

Annotated code