Fix assert format string in GrContext_colorTypeSupportedAsImage test.

Change-Id: I3a7aa0270d1e30095fda8e6a44059ecf826ac509
Reviewed-on: https://skia-review.googlesource.com/110100
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
2 files changed