`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'.

[weswigham]

We don't run this as part of our CI (though we probably should, since it's part of our LKG), so it's easy for us to break this target without realizing it.