Fixed depth range of WebVR projection matrices

Accidentally used a matrix that assumed a [0, 1] depth range (which is what D3D
uses) instead of OpenGL's [-1, 1] range. This effectively cut the depth
precision in half.

BUG=389343

Review-Url: https://codereview.chromium.org/2407413002
Cr-Commit-Position: refs/heads/master@{#424555}
1 file changed