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/variable/shadow_in_initializer.wren

@@ -6,6 +6,3 @@
     io.write(a) // expect: outer inner
   }
 }
-
-// TODO: Test referring to class name inside class for class at global scope
-// and in local scope.