tree-ir: Move labeled statements outside loops.

tests/compiler/dart2js/js_backend_cps_ir_control_flow_test.dart

 // Copyright (c) 2014, 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.
 
 // Tests of control flow statements.
 
 library control_flow_tests;
 
 import 'js_backend_cps_ir.dart';
 
@@ skipping 40 matching lines @@
 main() {
   for (int i = 0; foo(true); i = foo(i)) {
     print(1);
     if (foo(false)) break;
   }
   print(2);
 }""", """
 function() {
   var i = 0;
   L1:
-    while (true) {
-      if (P.identical(V.foo(true), true)) {
-        P.print(1);
-        if (!P.identical(V.foo(false), true)) {
-          i = V.foo(i);
-          continue L1;
-        }
-      }
-      P.print(2);
-      return null;
+    while (P.identical(V.foo(true), true)) {
+      P.print(1);
+      if (!P.identical(V.foo(false), true))
+        i = V.foo(i);
+      else
+        break L1;
     }
+  P.print(2);
+  return null;
 }"""),
 const TestEntry("""
 foo(a) => a;
 
 main() {
  if (foo(true)) {
    print(1);
  } else {
    print(2);
  }
@@ skipping 51 matching lines @@
 }""","""
 function() {
   P.identical(V.foo(), true) ? P.print("bad") : P.print("good");
   return null;
 }"""),
 ];
 
 void main() {
   runTests(tests);
 }