swift234

Speculatively change PlaygroundTransform to stop using FreeTypeVariableBinding::GenericParameters,
there are two possible situations here:

1) This code never runs on invalid code, in which case this argument does nothing.
2) This code does run on invalid code, and the type checker would crash as 
   TypeCheckExpr attempted to apply the solution.

This causes no regressions on the playground logger testsuite, but I'm not really confident
in this so I'll chat with Sean.



Swift SVN r30182