Add wasm compilation to CI
diff --git a/.travis.yml b/.travis.yml
index 45ea7a0..1ada298 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -7,6 +7,9 @@
     - 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
         - cargo test --features nightly