Rename GrContext::getFontAtlas to getFontAtlas_ForTesting

A trivial change but it does better indicate the nature of the method

Change-Id: I44a0e77dba28df892f4200496d78797ed5fd37df
Reviewed-on: https://skia-review.googlesource.com/7331
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
3 files changed