Only reposition the fallback vertices once.

We were shifting the verticies for the fallback subrun
twice when using paths to render. Once in regenerate,
and once using MapPoints.

BUG=chromium:913057

Change-Id: I4d2e977b0edbec22cbd57c45fe47c959d172908f
Reviewed-on: https://skia-review.googlesource.com/c/177920
Reviewed-by: Ben Wagner <bungeman@google.com>
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Herb Derby <herb@google.com>
3 files changed