Add Uint32 representation

tests/language/vm/uint32_add_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.
+// VMOptions=--optimization_counter_threshold=10
+
+import 'package:expect/expect.dart';
+
+trunc(x) => x & 0xFFFFFFFF;
+
+f(t, x) => t(x) + 1;
+
+g(t, x) => t(x + 1);
+
+// Foo should be entirely replaced by Uint32 operations. Running with
+// --trace-integer-ir-selection should result in:
+//    CheckStackOverflow:4()
+//    v22 <- UnboxUint32:14(v2)
+//    v24 <- UnboxUint32:14(v3)
+//    v6 <- BinaryUint32Op:14(+, v22 , v24 )
+//    v26 <- UnboxUint32:22(v4)
+//    v8 <- BinaryUint32Op:22(+, v6 , v26 )
+//    v28 <- UnboxUint32:30(v5)
+//    v10 <- BinaryUint32Op:30(+, v8 , v28 )
+//    v30 <- UnboxUint32:14(v21)
+//    v19 <- BinaryUint32Op:14(&, v10 , v30 )
+//    v32 <- BoxUint32:90(v19 )
+//    Return:38(v32 )
+foo(a, b, c, i) {
+  return trunc(a + b + c + i);
+}
+
+main() {
+  for (var i = 0; i < 20000; i++) {
+    Expect.equals(0x100000000, f(trunc, 0xFFFFFFFF));
+    Expect.equals(0x0, g(trunc, 0xFFFFFFFF));
+  }
+
+  var a = 0xFFFFFFFF;
+  var b = 0xCCCCCCCC;
+  var c = 0x33333335;
+
+  for (var i = 0; i < 20000; i++) {
+    Expect.equals(i, foo(a, b, c, i));
+  }
+}
+