Test emscripten via Cross (#302)

Part of addressing #275 

Signed-off-by: Joe Richey <joerichey@google.com>

.github/workflows/tests.yml

@@ -142,6 +142,7 @@ jobs:
           aarch64-unknown-linux-gnu,
           aarch64-linux-android,
           mips-unknown-linux-gnu,
+          wasm32-unknown-emscripten,
         ]
     steps:
       - uses: actions/checkout@v2
@@ -237,41 +238,6 @@ jobs:
           mv /tmp/wasmtime ~/.cargo/bin
       - run: cargo test --target wasm32-wasi
 
-  emscripten-tests:
-    name: Emscripten tests
-    runs-on: ubuntu-latest
-    env:
-      EMSDK_VERSION: 1.39.20 # Last emsdk compatible with Rust's LLVM 11
-    steps:
-      - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
-        with:
-          profile: minimal
-          toolchain: stable
-      - run: rustup target add wasm32-unknown-emscripten
-      - run: rustup target add asmjs-unknown-emscripten
-      - uses: Swatinem/rust-cache@v1
-      - name: Cache emsdk
-        id: cache-emsdk
-        uses: actions/cache@v2
-        with:
-          path: ~/emsdk
-          key: ${{ runner.os }}-${{ env.EMSDK_VERSION }}-emsdk
-      - name: Install emsdk
-        if: steps.cache-emsdk.outputs.cache-hit != 'true'
-        run: |
-          git clone https://github.com/emscripten-core/emsdk.git ~/emsdk
-          cd ~/emsdk
-          ./emsdk install $EMSDK_VERSION
-          ./emsdk activate $EMSDK_VERSION
-      - run: echo "$HOME/emsdk/upstream/emscripten" >> $GITHUB_PATH
-      - name: wasm test
-        run: cargo test --target=wasm32-unknown-emscripten --features=std
-      - name: asm.js test
-        run: | # Debug info breaks on asm.js
-          RUSTFLAGS="$RUSTFLAGS -C debuginfo=0"
-          cargo test --target=asmjs-unknown-emscripten --features=std
-
   build:
     name: Build only
     runs-on: ubuntu-latest