Canonicalize away simple arithmetic equivalences.

tests/language/arithmetic_canonicalization_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 canonicalization of simple arithmetic equivalences.
+
+main() {
+  for (var i = 0; i < 5000; i++) {
+    Expect.isTrue(mul1double(i) is double);
+    Expect.equals(i.toDouble(), mul1double(i));
+    Expect.equals(0.0, mul0double(i));
+    Expect.equals(i.toDouble(), add0double(i));
+
+    Expect.equals(i, mul1int(i));
+    Expect.equals(i, add0int(i));
+    Expect.equals(0, mul0int(i));
+    Expect.equals(0, and0(i));
+    Expect.equals(i, and1(i));
+    Expect.equals(i, or0(i));
+    Expect.equals(i, xor0(i));
+  }
+
+  Expect.isTrue(mul0double(double.NAN).isNaN);
+  Expect.isFalse(add0double(-0.0).isNegative);
+}
+
+mul1double(x) => 1.0 * x;
+mul0double(x) => 0.0 * x;
+add0double(x) => 0.0 + x;
+
+mul1int(x) => 1 * x;
+mul0int(x) => 0 * x;
+add0int(x) => 0 + x;
+and0(x) => 0 & x;
+or0(x) => 0 | x;
+xor0(x) => 0 ^ x;
+and1(x) => (-1) & x;