Removing dart2dart stuff is the most radical change, but there's also
a bunch of general clean up, some of it somewhat unrelated, but long
overdue.
I've focused on making the IR easier to read end-to-end.
For instance, I've stripped out a complicated assertion on InvokeMethod,
because it is distracting and hasn't paid off. AFAIK it never caught a
single bug, but a few times it has spuriously failed and needed
patching.
Some notable changes in the IR:
- Removed FieldDefinition, ConstructorDefinition, Initializers.
- Removed RootNode. There was only one subclass left.
- Removed Body. Has been inlined into FunctionDefinition.
- MutableVariable can no longer be a function parameter.
- Removed default parameter values and local constants from the IR.
I decided to keep nested functions for the time being because there is
a slight chance they might come in handy for async/await.
I'm not sure yet. We can strip them out later if they are not needed.
I've also left the subclassing JsIrBuilder <: IrBuilder for now,
even though the classes could be merged. Same with the visitor.
BUG=
R=kmillikin@google.com
Review URL: https://codereview.chromium.org//1155463005
Asger Feldthaus
ac4ab2b5b7