Fix detection of indexed properties in Object.defineProperty()

test/mjsunit/object-define-property.js

Index: test/mjsunit/object-define-property.js
===================================================================
--- test/mjsunit/object-define-property.js	(revision 14222)
+++ test/mjsunit/object-define-property.js	(working copy)
@@ -918,6 +918,11 @@
 assertFalse(desc.enumerable);
 assertFalse(desc.configurable);
 
+// Define non-array property, check that .length is unaffected.
+assertEquals(16, arr.length);
+Object.defineProperty(arr, '0x20', descElement);
+assertEquals(16, arr.length);
+
 // See issue 968: http://code.google.com/p/v8/issues/detail?id=968
 var o = { x : 42 };
 Object.defineProperty(o, "x", { writable: false });