dillon1000/react

Remove compiler flags

Remove our existing compiler flags since they were only being used for 
enabling/disabling passes to aid debugging and to simplify in preparation for 
the upcoming work on diagnostics and bailouts. Additionally with the new 
playground tabs disabling passes has become less necessary. In the future when 
we have actual compiler flags (eg tweaking optimization levels) we can add this 
back. 

I opted to keep the existing `CompilerResult` return value instead of just 
returning the optimized AST as we're still using `scopes` in our test fixtures.