Cache lookups at megamorphic call sites in optimized code.

tests/language/megamorphic_no_such_method_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 program for correct optimizations related to types fo allocated lists.
+
+// Classes to induce polymorphism of degree 10.
+class A0 {
+  test() => 0;
+}
+
+class A1 {
+  test() => 1;
+}
+
+class A2 {
+  test() => 2;
+}
+
+class A3 {
+  test() => 3;
+}
+
+class A4 {
+  test() => 4;
+}
+
+class A5 {
+  test() => 5;
+}
+
+class A6 {
+  test() => 6;
+}
+
+class A7 {
+  test() => 7;
+}
+
+class A8 {
+  test() => 8;
+}
+
+class A9 {
+  test() => 9;
+}
+
+// Class with no test method.
+class B { }
+
+test(obj) {
+  return obj.test(); 
+}
+
+main() {
+  // Trigger optimization of 'test' function.
+  List list = [new A0(), new A1(), new A2(), new A3(), new A4(),
+               new A5(), new A6(), new A7(), new A8(), new A9()];
+  for (int i = 0; i < 1000; i++) {
+    for (var obj in list) {
+      test(obj);
+    }
+  }
+  Expect.throws(() => test(new B()), (e) => e is NoSuchMethodError);
+}