[github] Use CMake to fetch deps in Emdawnwebgpu release jobs

Replace (most of) the custom dependency fetching in
package-emdawnwebgpu.sh in favor of DAWN_FETCH_DEPENDENCIES (which also
does a shallow fetch). Fetching the other dependencies surprisingly only
took an extra 22 seconds when tested on GitHub Actions, and it will be
needed if we start publishing prebuilt native binaries anyway.

This should fix the release jobs on GitHub Actions which currently fail
due to a missing Tint dependency on protobuf. (We don't actually need to
build Tint on that job, but we don't have a CMake option to disable
building Tint, and we don't need one if we just fetch all the deps.)

No-Try: true
Bug: 434707450
Change-Id: I49d4a7eb89e4cab638e0b801738055c341e9145c
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/255115
Commit-Queue: Kai Ninomiya <kainino@chromium.org>
Reviewed-by: Loko Kung <lokokung@google.com>

.github/workflows/package-emdawnwebgpu.sh

diff --git a/.github/workflows/package-emdawnwebgpu.sh b/.github/workflows/package-emdawnwebgpu.sh
index c1adc03..b8974f3 100755
--- a/.github/workflows/package-emdawnwebgpu.sh
+++ b/.github/workflows/package-emdawnwebgpu.sh
@@ -40,23 +40,22 @@
 PKG_FILE=emdawnwebgpu_pkg-${PKG_VERSION}.zip
 REMOTE_PORT_FILE=emdawnwebgpu-${PKG_VERSION}.remoteport.py
 
-# Initialize dependencies. We could use gclient for this, but then we still have to
-# install gclient, and it takes a long time. We only need a few deps for emdawnwebgpu.
-git submodule update --init --depth=1 third_party/abseil-cpp
-git submodule update --init --depth=1 third_party/googletest
+# Initialize emsdk so we can use emcmake. Other dependencies wll be downloaded
+# later via DAWN_FETCH_DEPENDENCIES (set in dawn-ci.cmake).
 git submodule update --init --depth=1 third_party/emsdk
 python3 tools/activate-emsdk
 
-# Build the package (which is not affected by the build type), and build the
-# link test in release mode (with Closure, which verifies the JS to some extent)
-mkdir -p out/wasm
-third_party/emsdk/upstream/emscripten/emcmake cmake -S=. -B=out/wasm -DCMAKE_BUILD_TYPE=Release
-make -j4 -C out/wasm emdawnwebgpu_pkg emdawnwebgpu_link_test
+# First build the link test in debug mode as a basic test.
+third_party/emsdk/upstream/emscripten/emcmake cmake -S=. -B=out/wasm \
+    -C=.github/workflows/dawn-ci.cmake \
+    -DCMAKE_BUILD_TYPE=Debug
+make -j4 -C out/wasm emdawnwebgpu_link_test
 
-# Also build the link test in debug mode.
-mkdir -p out/wasm-debug
-third_party/emsdk/upstream/emscripten/emcmake cmake -S=. -B=out/wasm-debug -DCMAKE_BUILD_TYPE=Debug
-make -j4 -C out/wasm-debug emdawnwebgpu_link_test
+# Switch the build type (in-place to save time), rebuild the link test (this
+# time with Closure, which verifies the linked JS to some extent), and build the
+# final package (which is not actually affected by build type).
+cmake -S=. -B=out/wasm -DCMAKE_BUILD_TYPE=Release
+make -j4 -C out/wasm emdawnwebgpu_pkg emdawnwebgpu_link_test
 
 # Get variables for documentation.
 SHA=$(git rev-parse HEAD)