raster image of pservers-grad-19-b

This test shows rectangles filled with animated gradient who inherits some of their properties: stop-color, stop-opacity. The correct result should show: - the top-left rectangle filled initially with a linear green-to-red gradient and turning into a solid green color after 5s. - the top-right rectangle filled initially with a green gradient fully opaque on the left and half transparent on the right, but after 5s the rectangle should be filled with a fully opaque solid green. - the bottom-left rectangle filled with a static green-to-black opaque gradient - the bottom-right rectangle initially filled with a green-to-yellow fully-opaque gradient animated and turning into a fully-opaque green solid color. Animations numbered a4 to a7 should have no impact.