This fixes up some other build flag options:
- font-specific js code is correctly omitted when no_font is set
- SKP serialization is only compiled in debug (or with flag).
Bug: skia:9733
Change-Id: Ifdbd2ddac278cfcefa842f6d4826d5429b6ed64b
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/262137
Reviewed-by: Kevin Lubick <kjlubick@google.com>
