Fail on ignored inline types

I've been experimenting with inline types such as:

``` javascript
var myFoo = function /** number */ (x) { return "a"; }
```

Now this isn't supported (https://github.com/google/closure-compiler/issues/1063) and silently passes. Making it hard to feel one's way around the correct syntax.

I propose a check condition which fails when a single-line potential inline type annotation is found that has no effect:

``` javascript
... /** something */ someJsCode
someJsCode /** something */ ...
```

I'd do it myself with a PR but it's a bit out of my depth without some pointers.