Fix bug when a variable is used in try/catch and accessed trough HFieldGet and HFieldSet: reference…

tests/language/scoped_variables_try_catch_test.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.
+
+// Test that try/catch does not shadow a variable at runtime.
+
+main() {
+  var a = bar();
+  try {
+    a = bar();
+  } catch (var e) {
+  }
+  Expect.equals(42, a);
+
+  {
+    var a = foo();
+    try {
+      a = foo();
+    } catch (var e) {
+    }
+    Expect.equals(54, a);
+  }
+
+  Expect.equals(42, a);
+}
+
+bar() => 42;
+foo() => 54;