Add wasm compilation to CI

Author: alexcrichton

.travis.yml

@@ -6,6 +6,9 @@ matrix:
     - rust: 1.15.0
     - rust: stable
     - rust: beta
+    - rust: nightly
+      install: rustup target add wasm32-unknown-unknown
+      script: cargo test --target wasm32-unknown-unknown --no-run
     - rust: nightly
       script:
         - cargo test