travis: test JS backend

.travis.yml

@@ -76,6 +76,11 @@ script:
     fi
   - |
     if [[ "${TRAVIS_OS_NAME}" == "osx" ]]; then
+      # Build Vid
       git clone https://github.com/vlang/vid
       cd vid && ../v -debug -o vid .
+
+      # Build hi.js
+      echo "println('Hello from V.js')" > hi.js
+      v -o hi.js hi.v && node hi.js
     fi

compiler/cc.v

@@ -33,6 +33,7 @@ fn (v mut V) cc() {
 				ret := os.system('$vjs_path -o $v.out_name $v.dir')
 				if ret == 0 {
 					println('Done. Run it with `node $v.out_name`')
+					println('JS backend is at a very early stage.')
 				}	
 			}
 		}