[refactor] integrate Transformer (manager for transform commands) to compiler
rebuild boostrap compiler to use: __CLASS__
add failing tests
add support for compile-time constants; can be set using --define name=var, accessible via JSX.ENV["key"]
Merge branch 'kazuho/issues/compile-time-constants' (close #304)
add failing test
implement fold-const optimization for comparison against null
Merge branch 'kazuho/fold-null-vs-null'