The FloatToHalf() function in "es31cVertexAttribBindingTests.cpp" will
attempt to right-shift more than the number of bits in an integer
(i.e. by 70) when converting 0.0f to GLhalf.

Bug: angleproject:5500
Change-Id: I587e71a2cb1377b95ed74a1bba5f4ceef6a4a516
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2618665
Commit-Queue: Ian Elliott <ianelliott@google.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Yuly Novikov <ynovikov@chromium.org>