Implement support for CHROMIUM_NV_path_rendering pseudo extension

Implement support for CHROMIUM_path_rendering pseudo extension

Implement support for NV_path_rendering by using
CHROMIUM_path_rendering pseudo-extension.

The pseudo-extension brings following into GL ES context:
 * the needed NV_path_rendering functions
 * the needed matrix functions
 * gl_TexCoord in GLSL, as long as #extension
   CHROMIUM_path_rendering is specified.

The pseudo-extension is advertised with
"GL_CHROMIUM_path_rendering" extension string.

BUG=chromium:344330