`gulp lssl` needs more dependencies

Running `gulp clean; gulp lssl` results in compiler errors. (`jake clean; jake lssl` doesn't work either.)
The specific errors are:

```
C:/Users/andy/work/typescript/src/services/utilities.ts(839,77): error TS2304: Cannot find name 'LanguageServiceShimHost'.
C:/Users/andy/work/typescript/src/services/utilities.ts(839,77): error TS2304: Cannot find name 'LanguageServiceShimHost'.
```
