Restore r1383: Fix method resolution to warn about things that don't exist on the declared type.

frog/tree.dart

Index: frog/tree.dart
diff --git a/frog/tree.dart b/frog/tree.dart
index bdc4cdbbf11eee23d7d0722b92405aa248efa6f3..dd846941282bb61cd899cf7705abdb868612c651 100644
--- a/frog/tree.dart
+++ b/frog/tree.dart
@@ -27,6 +27,7 @@ class Definition extends Statement {
   Definition(SourceSpan span): super(span) {}
 
   List<TypeParameter> get typeParameters() => null;
+  String get nativeType() => null;

[jimhug, 2011/11/10 15:47:21]

This puzzled me for a while - even though I wrote the original property that
this is <whatever the opposite of overrides is>..  Even with the explicit return
type of String, I kept trying to understand why we'd be putting a [Type] member
on something in the AST.  TODO - This should be renamed to nativeTypeName to
avoid future confusion.

 }
 
 /** The base type for statements. */