This change broke standalone build on Windows. Two casts from double to
GLfloat were missing.

This reverts commit 7aa4cae2.

BUG=angleproject:891

Change-Id: I69cf773c940fd43b06f21c1ee86e60bac6825684
Reviewed-on: https://chromium-review.googlesource.com/303352Reviewed-by: Olli Etuaho <oetuaho@nvidia.com>
Tested-by: Olli Etuaho <oetuaho@nvidia.com>