Create a typedef

[zoechi]

I haven't found a way to do that

[zoechi]

Seems there is also no way to create one using xxxx.raw()

[matanlurey]

Unfortunately it's hard to make xxxx.raw too generic.

I might take a shot at doing something like RawAstBuilder:

abstract class RawAstBuilder<T extends AstNode> {}

At minimum it will let us get to 1.0-final without implementing every feature in Dart.

[zoechi]

I expected Raw('some string') to implement every builder interface and then just emit the string,
but I haven't investigated enough yet to fully understand how the source is generated.