Fix Issue 326. Handle sorting of non-array objects correctly.

test/mjsunit/array-sort.js

Index: test/mjsunit/array-sort.js
diff --git a/test/mjsunit/array-sort.js b/test/mjsunit/array-sort.js
index dfa45906ec7bfde093bd3ff90cb26eeaf135bdfa..54435945b649442e3ac724bfe25452531313afac 100644
--- a/test/mjsunit/array-sort.js
+++ b/test/mjsunit/array-sort.js
@@ -152,3 +152,24 @@ function TestArraySortingWithUnsoundComparisonFunction() {
 }
 
 TestArraySortingWithUnsoundComparisonFunction();
+
+function TestSparseNonArraySorting(length) {
+  assertTrue(length > 101);
+  var obj = {length: length};
+  obj[0] = 42;
+  obj[10] = 37;
+  obj[100] = undefined;
+  obj[length - 1] = null;
+  Array.prototype.sort.call(obj);
+  assertEquals(length, obj.length, "objsort length unaffected");
+  assertEquals(37, obj[0], "objsort smallest number");
+  assertEquals(42, obj[1], "objsort largest number");
+  assertEquals(null, obj[2], "objsort null");
+  assertEquals(undefined, obj[3], "objsort undefined");
+  assertTrue(3 in obj, "objsort undefined retained");
+  assertFalse(4 in obj, "objsort non-existing retained");
+}
+
+TestSparseNonArraySorting(5000);
+TestSparseNonArraySorting(500000);
+TestSparseNonArraySorting(Math.pow(2, 31) + 1);