Support break and labeled statements.

frog/tests/leg_only/src/LabelTest.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // A break label must be declared where it's used.
 undeclaredBreakLabel1() {
   foo: { break bar; break foo; }  /// 01: compile-time error
 }
 
 undeclaredBreakLabel2() {
@@ skipping 31 matching lines @@
 // Implicit break targets are not captured by closures.
 noncaptureBreak() {
   while(true) (() { break; })();  /// 08: compile-time error
 }
 
 // Implicit continue targets are not captured by closures.
 noncaptureContinue() {
   while(true) (() { continue; })();  /// 09: compile-time error
 }
 
-// Duplicate labels are reported as a warning only.
-duplicateLabels() {
-  foo: {          /// 10: compile-time error
-    foo: {        /// 10: continued
-      return;     /// 10: continued
-      break foo;  /// 10: continued
-    }             /// 10: continued
-  }               /// 10: continued
-}
-
-
-// Unused  labels are reported as a warning only.
-unusedLabels() {
-  foo: { return; }  /// 11: compile-time error
-}
-
-
 main() {
   undeclaredBreakLabel1();
   undeclaredBreakLabel2();
   noBreakTarget();
   undeclaredContinueLabel();
   noContinueTarget();
   wrongContinueLabel();
   noncaptureLabel();
   noncaptureBreak();
   noncaptureContinue();
-  duplicateLabels();
-  unusedLabels();
 }