Fix a bunch of test TODOs.

- Added a bunch of tests.
- Removed some TODOs for stuff that's already done.
- Made list literals handle newlines better.

test/field/multiple.wren

@@ -24,7 +24,6 @@ foo.write
 // expect: 4
 // expect: 5
 
-// TODO: Inherited fields.
 // TODO: Trying to get or set a field outside of a class.
 // TODO: Fields in nested classes.
 // TODO: Closing over fields.