Add a "Label" Node around an Identifier that is being used as a label.

lib/compiler/implementation/ssa/builder.dart

Index: lib/compiler/implementation/ssa/builder.dart
diff --git a/lib/compiler/implementation/ssa/builder.dart b/lib/compiler/implementation/ssa/builder.dart
index e8d852fa6b589eb91fbc1d910f5e07bf80079673..cec566830ee2eb7183b6f1b71db47faa4ad26bd6 100644
--- a/lib/compiler/implementation/ssa/builder.dart
+++ b/lib/compiler/implementation/ssa/builder.dart
@@ -2815,6 +2815,13 @@ class SsaBuilder implements Visitor {
     handleLoop(node, buildInitializer, buildCondition, () {}, buildBody);
   }
 
+  visitLabel(Label node) {
+    // We visit labels in different roles depending on whether it's a
+    // label introduction or a label reference, so it's handled by the
+    // containing statement.
+    unreachable();

[ahe, 2012/05/10 11:52:30]

I really don't like using this method. You have a node, so use it to report a
nice error message.

[Lasse Reichstein Nielsen, 2012/05/10 12:14:20]

True, also the comment is no longer valid.
Using internalError like in some other places.

+  }
+
   visitLabeledStatement(LabeledStatement node) {
     Statement body = node.getBody();
     if (body is Loop || body is SwitchStatement) {