Clean up GrGLIRect

Renames fLeft/fBottom to fX/fY, removes the GL calls, and adds static
"MakeRelativeTo" methods.

Bug: skia:
Change-Id: I7a09673f29a771a35cc52ec049421591d6077659
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/239413
Reviewed-by: Greg Daniel <egdaniel@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>
2 files changed