Implement support for CHROMIUM_path_rendering pseudo extension

Implement support for CHROMIUM_path_rendering pseudo extension

Implement support for path rendering in Chromium through
CHROMIUM_path_rendering pseudo extension.

The extension defines a new pseudo-gl function,
BindFragmentInputLocation. This behaves similarly to the
BindUniformLocation pseudo-gl function. The idea is to assign fragment
input location to a fragment input before linking the program.

BUG=chromium:344330

Review URL: https://codereview.chromium.org/1192663002