Check wasm target is working by running 'cargo check' on the demo_web package (#36)

.github/workflows/rust.yml

@@ -17,6 +17,22 @@ jobs:
         with:
           command: check
 
+  check_demo_web:
+    name: Check demo_web
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: stable
+          override: true
+      - run: rustup target add wasm32-unknown-unknown
+      - uses: actions-rs/cargo@v1
+        with:
+          command: check
+          args: -p demo_web --target wasm32-unknown-unknown
+
   test:
     name: Test Suite
     runs-on: ubuntu-latest