Improve ScanJsonNumber.

src/array.js

 // Copyright 2010 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 1000 matching lines @@
 
 
 function ArrayIndexOf(element, index) {
   var length = TO_UINT32(this.length);
   if (length == 0) return -1;
   if (IS_UNDEFINED(index)) {
     index = 0;
   } else {
     index = TO_INTEGER(index);
     // If index is negative, index from the end of the array.
-    if (index < 0) index = length + index;
-    // If index is still negative, search the entire array.
-    if (index < 0) index = 0;
+    if (index < 0) {
+      index = length + index;
+      // If index is still negative, search the entire array.
+      if (index < 0) index = 0;
+    }
   }
   var min = index;
   var max = length;
   if (UseSparseVariant(this, length, true)) {
     var intervals = %GetArrayKeys(this, length);
     if (intervals.length == 2 && intervals[0] < 0) {
       // A single interval.
       var intervalMin = -(intervals[0] + 1);
       var intervalMax = intervalMin + intervals[1];
       min = MAX(min, intervalMin);
@@ skipping 195 matching lines @@
     "lastIndexOf", getFunction("lastIndexOf", ArrayLastIndexOf, 1),
     "reduce", getFunction("reduce", ArrayReduce, 1),
     "reduceRight", getFunction("reduceRight", ArrayReduceRight, 1)
   ));
 
   %FinishArrayPrototypeSetup($Array.prototype);
 }
 
 
 SetupArray();