Revert^2 "Support alpha for SurfaceView"

3fde6cee

This is the same CL as the original CL, with the exception that SurfaceView#isZOrderedOnTop checks mRequestedSubLayer, rather than mSubLayer.

This is to fix a CTS failure with InlineContentViewTest#testSetZOrderedOnTop, which set the Z order of an offscreen SurfaceView without binding it to a layout.

Change-Id: Ifdfa710d87f7ea4c333505ffdcc7fbff06245fba