Fix bug with range of shift operations.

tests/language/vm/optimized_shl_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";
+
+// Test truncating left-shift that can deoptimize.
+// Regression test for issue 19330.
+
+test_shl(w, x) {
+  x += 1;
+  return w << x & 0xff ;
+}
+
+main() {
+  for (var i = 0; i < 20; i++) test_shl(i, i % 10);
+  Expect.equals(4, test_shl(1, 1));
+}
+