- Correctly handle negative constant indices when

tests/language/optimized_constant_array_string_access_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.
 
 import "package:expect/expect.dart";
 
 // Test optimized constant string and constant array access.
 
 int testConstantStringAndIndexCodeUnitAt() {
   int test(b) {
     if (b) return "hest".codeUnitAt(400);
     return "hest".codeUnitAt(2);
   }
 
   Expect.throws(() => test(true));
   for (int i = 0; i < 10000; i++) test(false);
   Expect.throws(() => test(true));
 }
 
 
 int testConstantArrayAndIndexAt() {
-  int test(b) {
+  int testPositive(b) {
     var a = const [1,2,3,4];
     if (b) return a[400];
     return a[2];
   }
 
-  Expect.throws(() => test(true));
-  for (int i = 0; i < 10000; i++) test(false);
-  Expect.throws(() => test(true));
+  int testNegative(b) {
+    var a = const [1,2,3,4];
+    if (b) return a[-1];
+    return a[2];
+  }
+
+  Expect.throws(() => testPositive(true));
+  for (int i = 0; i < 10000; i++) testPositive(false);
+  Expect.throws(() => testPositive(true));
+
+  Expect.throws(() => testNegative(true));
+  for (int i = 0; i < 10000; i++) testNegative(false);
+  Expect.throws(() => testNegative(true));
 }
 
 
 foo(a) {
   if (a == 1) { return 2; }
   var aa = const [1, 2];
   return aa[2.3];
 }
 
 
 int testNonSmiIndex() {
   for (int i = 0; i < 10000; i++) { foo(1); }
   Expect.throws(() => foo(2));
 }
 
 
 main() {
   testConstantStringAndIndexCodeUnitAt();
   testConstantArrayAndIndexAt();
   testNonSmiIndex();
 }