Lambda type in Lambda argument causes infinite loop

Code such as:
```
(f: (s) => boolean) => f
```
will cause ng2-mode's `ng2-ts--highlight-lambda-args-fn` to enter an infinite loop.

Initially I think this is due to `ng2-ts--inside-lambda-args-p` finding the first `=>` and not the lambda's own `=>`

I am working on a patch and will post an update with it as soon as I can.