++
Removing the static import that caused exception on compilation
CHECK_TYPES injected through imports
DescriptorRenderer can now render flexible types for code (i.e. `ft<L, U>`)
toString() for easier debugging
Clean up declarations of runReadAction() etc
KT-6059 Regression: irrelevant compiler error on trait inheritance (worked in M8)

 #KT-6059 Fixed
~ extra test (requires platform types in tests)
KT-6077 Compiler does not issue error on unsafe access to ArrayList with nullable values

  #KT-6077 Fixed
Compilation errors fixed