Test which verifies the basic facilities of feComposite.

This test uses the following elements: <path>, <use>, <linearGradient>, <filter> with, an enable-background attribute, <feFlood>, <feComposite>, <feMerge>

The test case shows six pairs of overlapping triangles depicting the six different feComposite operators. The first row shows compositing when both triangles have opacity=1. The second row shows compositing when both triangles have opacity=.5. The six columns illustrate the six types of compositing operations.