Support remaping of pair location inside materializations for slow paths.

tests/standalone/pair_location_remaping_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.
+// Test that pair locations are remaped in slow path environments.
+// VMOptions=--optimization_counter_threshold=10 --no-use-osr
+
+import "package:expect/expect.dart";
+
+class A {
+  final f;
+  A(this.f);
+}
+
+foo(i) {
+  var j = 0x7fffffffffffffff + i;
+  var c = new A(j);  // allocation will be sunk
+  var r = 0;
+  for (var k = 0; k < 10; k++) {
+    if ((j & (1 << k)) != 0) {
+      r++;
+    }
+  }
+  return c.f - r;
+}
+
+main() {
+  for (var i = 0; i < 1000; i++) {
+    Expect.equals(0x7fffffffffffffff - 10, foo(0));
+  }
+}