Fix fragile argument name parsing


The lastArgumentName function's regex would fail on many single-line functions.  For example:

```javascript
function F(req, res, _) {   return fstreamline_F__.apply(this, arguments);  }
  -> args [ 'this', ' arguments' ]
```

(The above structure is now generated from streamline when using the fibers or generators backend.)  This commit fixes this with non-greedy repitition, also simplifying the regex in the process:

```javascript
function F(req, res, _) {   return fstreamline_F__.apply(this, arguments);  }
  -> args [ 'req', ' res', ' _' ]
```

This also fixes the case where the argument list is split across lines.