Reverese attempted optimization of array sort.

src/array.js

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 665 matching lines @@
       return;
     }
     var pivot_index = $floor($random() * (to - from)) + from;
     var pivot = a[pivot_index];
     // Pre-convert the element to a string for comparison if we know
     // it will happen on each compare anyway.
     var pivot_key =
       (custom_compare || %_IsSmi(pivot)) ? pivot : ToString(pivot);
     // Issue 95: Keep the pivot element out of the comparisons to avoid
     // infinite recursion if comparefn(pivot, pivot) != 0.
-    var low_end = from; // Upper bound of the elements lower than pivot.
-    var high_start = to; // Lower bound of the elements greater than pivot.
-    var eq_start = to - 1; // Lower bound of elements equal to pivot.
-    a[pivot_index] = a[eq_start];
-    a[eq_start] = pivot;
-    // From eq_start to high_start are elements equal to the pivot
-    // (including the pivot).
-    // From low_end to eq_start are elements that have not been compared yet.
-    while (low_end < eq_start) {
-      var element = a[low_end];
+    a[pivot_index] = a[from];
+    a[from] = pivot;
+    var low_end = from;   // Upper bound of the elements lower than pivot.
+    var high_start = to;  // Lower bound of the elements greater than pivot.
+    // From low_end to i are elements equal to pivot.
+    // From i to high_start are elements that haven't been compared yet.
+    for (var i = from + 1; i < high_start; ) {
+      var element = a[i];
       var order = Compare(element, pivot_key);
       if (order < 0) {
+        a[i] = a[low_end];
+        a[low_end] = element;
+        i++;
         low_end++;
       } else if (order > 0) {
-        eq_start--;
         high_start--;
-        a[low_end] = a[eq_start];
-        a[eq_start] = a[high_start];
+        a[i] = a[high_start];
         a[high_start] = element;
       } else {  // order == 0
-        eq_start--;
-        a[low_end] = a[eq_start];
-        a[eq_start] = element;
+        i++;
       }
     }
     QuickSort(a, from, low_end);
     QuickSort(a, high_start, to);
   }
 
   var old_length = ToUint32(this.length);
   if (old_length < 2) return this;
 
   %RemoveArrayHoles(this);
@@ skipping 213 matching lines @@
     ArrayEvery: 1,
     ArrayMap: 1,
     ArrayIndexOf: 1,
     ArrayLastIndexOf: 1,
     ArrayPush: 1
   });
 }
 
 
 SetupArray();