Check that a glyph will fit in the atlas instead of a bogus check

I made a transcription error about 7 mo. ago. This corrects the error.

Change-Id: Icbe814a9e44748778bf988840fc2fc7ab9e8fa86
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/200500
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Herb Derby <herb@google.com>
Cherry-Pick: fbf260df762d773602fea4cb4713e5ed96e9983f
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/200929
Reviewed-by: Herb Derby <herb@google.com>