There was a break that was solved by adding -lGL to our link
steps. I discovered a few extra flags to aid in debugging builds
and I've left those in (they aren't too noisy IMO).
This changes the base dockerfile to use the official emscripten one.
Code size delta for full build is +5 kb
For future reference, emsdk decides which "library JS" files to
pull in using a83ba99d60/tools/building.py (L1553)
Those JS files live in src (e.g. a83ba99d60/src/library_html5_webgl.js (L222))
and define functions that the C++ code can call.
I'd like to follow-up on what -lEGL is doing.
Also, since the new image no longer has depot_tools, we need
to make docker/skia-wasm-release/Dockerfile install it.
Change-Id: I5a38e61e5080e9c4cb1e0a7e031509bcb107ff86
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/311726
Reviewed-by: Nathaniel Nifong <nifong@google.com>
157577b866