This built-in uniform wasn't being collected in VariableInfo.cpp.
Also remove the existing workaround for D3D gl_DepthRange
collection.

BUG=angleproject:991
BUG=478570

Change-Id: Ie254132e37c307323ba9e6e1705d138eea67b520
Reviewed-on: https://chromium-review.googlesource.com/268524Tested-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Zhenyao Mo <zmo@chromium.org>