Cleanup legacy NVPR-related definitions

Fixed-function NVPR codepaths were removed a while ago. Only NVPR API
version 1.3 (PathFragmentInputGen) was left working. Remove
backwards-compatibility code that was left behind.

Remove some NVPR API function typedefs that were left from initial
commits.

Remove PathCoords function pointer from GrGLInterface, it has
never been called and causes problems in the future, since it will
not be implemented in the Chromium pseudo extension.

Review URL: https://codereview.chromium.org/1177243004
7 files changed