The shift-amount must not be anded with 31.

tests/language/bit_shift_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.
+
+constants() {
+  Expect.equals(0, 499 >> 33);
+  Expect.equals(0, (499 << 33) & 0xFFFFFFFF);
+}
+
+foo(i) {
+  if (i != 0) {
+    y--;
+    foo(i - 1);
+    y++;
+  }
+}
+
+var y;
+
+// id returns [x] in a way that should be difficult to predict statically.
+id(x) {
+  y = x;
+  foo(10);
+  return y;
+}
+
+interceptors() {
+  Expect.equals(0, id(499) >> 33);
+  Expect.equals(0, (id(499) << 33) & 0xFFFFFFFF);
+}
+
+speculative() {
+  var a = id(499);
+  for (int i = 0; i < 1; i++) {
+    Expect.equals(0, a >> 33);
+    Expect.equals(0, (a << 33) & 0xFFFFFFFF);
+  }
+}
+
+// JavaScript shifts by the amount modulo 32. That is x << y is equivalent to
+// x << (y & 0x1F). Dart does not.
+main() {
+  constants();
+  interceptors();
+  speculative();
+}