Started working on gradient opacity test for new mapper

Change-Id: I12a4edc644044acae591a4afb8907745f2d7baf0
Added new gradient opacity test

Change-Id: Ibeb2a589e0bd85fb3b31cfdbc26a568bb9a2e138
Test the new mapper for gradient opacity support

Change-Id: I73158e89943e8f991b08c14d62e6df24887ef6de
BUG: Fix an issue in the shader code that supports gradient opacity

Change-Id: I1db36cdc79ccf3b890e4018c5ae3c249f3eb10d6