[graphite] Check for null recorder before caps

This was causing the imagemakesubset GM to crash when running on any
raster surface config if the graphite build was turned on.

Change-Id: I7caa4f15342cf8927521cbadbac2d9618e19efd9
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/834876
Auto-Submit: Michael Ludwig <michaelludwig@google.com>
Reviewed-by: James Godfrey-Kittle <jamesgk@google.com>
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
1 file changed