fix to not assign uninitialized array to string

fixes https://skia-review.googlesource.com/c/6727/

BUG=skia:

Change-Id: I8b8f79174ec32a1fa9d17dec4f5c812f70b83fbe
Reviewed-on: https://skia-review.googlesource.com/6731
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Reed <reed@google.com>
1 file changed