When canonicalizing branch on StrictCompare ensure that branch gets correct environment.

tests/language/branch_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 that branch fusion correctly sets branch environment for comparisons
+// that require unboxing and does not fuse branches that can deoptimize.
+
+var sideEffect = true;
+
+barDouble(a, b) {
+  sideEffect = false;
+  final result = (a == b);
+  sideEffect = !sideEffect;
+  return result;
+}
+fooDouble(a, b) => barDouble(a, b) ? 1 : 0;
+
+barMint(a, b) {
+  sideEffect = false;
+  final result = (a == b);

[Florian Schneider, 2013/02/13 14:08:43]

Why "final" here and "var" below in barPoly?

[Vyacheslav Egorov (Google), 2013/02/13 14:10:19]

cleaned up

+  sideEffect = !sideEffect;
+  return result;
+}
+fooMint(a, b) => barMint(a, b) ? 1 : 0;
+
+class A {
+  operator == (other) => identical(this, other);
+}
+
+class B extends A {
+}
+
+class C extends A {
+}
+
+barPoly(a, b) {
+  sideEffect = false;
+  var x = a == b;
+  sideEffect = !sideEffect;
+  return x;
+}
+
+fooPoly(a, b) {
+  var result = barPoly(a, b) ? 1 : 0;
+  return result;
+}
+
+main () {
+  final a = 1.0;
+  final b = 1 << 62;
+  final x = new A(), y = new B(), z = new C();
+  for (var i = 0; i < 10000; i++) {
+    Expect.equals(1, fooDouble(a, a));
+    Expect.isTrue(sideEffect);
+    Expect.equals(0, fooMint(b, 0));
+    Expect.isTrue(sideEffect);
+    Expect.equals(1, fooPoly(x, x));
+    Expect.equals(0, fooPoly(y, x));
+  }
+  Expect.equals(1, fooDouble(z, z));
+  Expect.isTrue(sideEffect);
+  Expect.equals(1, fooMint(z, z));
+  Expect.isTrue(sideEffect);
+  Expect.equals(1, fooPoly(z, z));
+  Expect.isTrue(sideEffect);
+}
+
+
+