[canvaskit] Add files needed for npm release

Backport changes to pathkit too.

Bug: skia:
Change-Id: Id10f9ac52dc7d08f044eee1eeacc8737f1cd96f4
Reviewed-on: https://skia-review.googlesource.com/c/177894
Reviewed-by: Heather Miller <hcm@google.com>
13 files changed