Fix crash in compiler when we are generating a bailout method where a loop contains continue/break/…

tests/language/bailout5_test.dart

+// Copyright (c) 2013, 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.
+
+// Test to make sure the bailout environment in dart2js is correct.
+
+var global;
+
+class A {
+  var array;
+
+  initArray() {
+    return global[0] == null ? [null] : {}; 
+  }
+
+  bar() {
+    array = initArray();
+    do {
+      var element = array[0]; // bailout here
+      if (element is Map) continue;
+      if (element == null) break;
+    } while (true);
+    return global[0]; // bailout here
+  }
+
+  baz() {
+    do {
+      var element = bar();
+      if (element == null) return global[0]; // bailout here
+      if (element is Map) continue;
+      if (element is num) break;
+    } while (true);
+    return global[0]; // bailout here
+  }
+}
+
+
+void main() {
+  global = [1];
+  for (int i = 0; i < 2; i++) {
+    Expect.equals(1, new A().baz());
+    Expect.equals(1, new A().bar());
+  }
+  global = {};
+  for (int i = 0; i < 2; i++) {
+    Expect.equals(null, new A().baz());
+    Expect.equals(null, new A().bar());
+  }
+
+  global[0] = 42;
+  for (int i = 0; i < 2; i++) {
+    Expect.equals(42, new A().baz());
+    Expect.equals(42, new A().bar());
+  }
+}