Faster 64-bit right-shift for the ia32 compiler.

tests/language/bit_operations_test.dart

Index: tests/language/bit_operations_test.dart
===================================================================
--- tests/language/bit_operations_test.dart	(revision 13286)
+++ tests/language/bit_operations_test.dart	(working copy)
@@ -54,12 +54,13 @@
     TestPositiveValueShifts();
     TestNoMaskingOfShiftCount();
     TestNegativeCountShifts();
-    for (int i = 0; i < 1000; i++) {
-      TestCornerCasesLeftShifts();
+    for (int i = 0; i < 10000; i++) {
+      TestCornerCasesRightShifts();
+      TestRightShift64Bit();
     }
   }
 
-  static void TestCornerCasesLeftShifts() {
+  static void TestCornerCasesRightShifts() {
     var v32 = 0xFF000000;
     var v64 = 0xFF00000000000000;
     Expect.equals(0x3, v32 >> 0x1E);
@@ -70,6 +71,11 @@
     Expect.equals(0x0, v64 >> 0x40);
   }
 
+  static void TestRightShift64Bit() {
+    var t = 0x1ffffffff;
+    Expect.equals(0xffffffff, t >> 1);
+  }
+
   static void TestNegativeCountShifts() {
     bool throwOnLeft(a, b) {
       try {