Use InternalArray in Object.getOwnPropertyNames() implementation

test/mjsunit/object-get-own-property-names.js

Index: test/mjsunit/object-get-own-property-names.js
diff --git a/test/mjsunit/object-get-own-property-names.js b/test/mjsunit/object-get-own-property-names.js
index 33aa85ef15d6122fc3038100a6e51dab6a9f7b1b..40052ada1cd71bf411f77a29b701434fbf83cc34 100644
--- a/test/mjsunit/object-get-own-property-names.js
+++ b/test/mjsunit/object-get-own-property-names.js
@@ -77,6 +77,13 @@ propertyNames.sort();
 assertEquals(1, propertyNames.length);
 assertEquals("getter", propertyNames[0]);
 
+// Check that implementation does not access Array.prototype.
+var savedConcat = Array.prototype.concat;
+Array.prototype.concat = function() { return ['foo', 'bar']; }
+propertyNames = Object.getOwnPropertyNames({});
+assertEquals(0, propertyNames.length);
+Array.prototype.concat = savedConcat;
+
 try {
   Object.getOwnPropertyNames(4);
   assertTrue(false);