Cleanup of large text rendering.

* Switch all path glyphs to be rendered as part of the fBigGlyphs
(now fPathGlyphs) system
* Use one flush command for both cached and throwaway blobs
* Store and render path glyphs per run rather than one list for the
entire blob (fixes a layering bug)
* Fix bug with scaled fallback glyphs, where fallback glyphs were
trying to use more than one descriptor

Bug: skia:7562
Change-Id: Ic3d01887e2203a844102a04afe8674a16149b4bb
Reviewed-on: https://skia-review.googlesource.com/102400
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
7 files changed