Fix size problem spotted by sra@, where iae and ioore were always put in the codegen work list.

tests/compiler/dart2js/size_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.
+
+import "mock_compiler.dart";
+import "compiler_helper.dart";
+
+const String TEST = "main() => [];";
+
+const String DEFAULT_CORELIB_WITH_LIST = r'''
+  class Object {}
+  class bool {}
+  abstract class List {}
+  class num {}
+  class int {}
+  class double {}
+  class String {}
+  class Function {}
+  class Type {}
+  class Map {}
+''';
+
+main() {
+  String generated = compileAll(TEST, coreSource: DEFAULT_CORELIB_WITH_LIST);
+  MockCompiler compiler = new MockCompiler();
+  var backend = compiler.backend;
+
+  // Make sure no class is emitted.
+  Expect.isFalse(generated.contains(backend.emitter.defineClassName));
+}