Fix interpreter __proto__ bug
Update comments to refer to correct spec location; Add java-doc to some classes
Remove obscure `negative values mean undefined` logic
Add helper to check whether a function is a generator function
Change field from package to private access
Add final modifier to classes
Repeat flatten process and handle arrow expressions
Add comments and add 'final' to classes
Generate multiple classes if the number of methods exceeds a certain limit
Use new FunctionNode#isGenerator() helper
Execute finally-block to restore legacy properties for all throwables
Add some more tests for Promise.cast()
Add tests for uninitialised objects edge cases
Add test suite for compiler bugs
%ThrowTypeError% is an anonymous function object