Fix Object.freeze on dictionary-backed arrays to properly freeze elements

test/mjsunit/object-freeze.js

Index: test/mjsunit/object-freeze.js
diff --git a/test/mjsunit/object-freeze.js b/test/mjsunit/object-freeze.js
index 6a177a4441fcc2ecb34a3dc16e07fc101ce267c2..619ada006ea710e1a26ba25b67b3e6ecdfed1530 100644
--- a/test/mjsunit/object-freeze.js
+++ b/test/mjsunit/object-freeze.js
@@ -253,3 +253,9 @@ var func = function(arg) {
 };
 func('hello', 'world');
 func('goodbye', 'world');
+
+// Freezing sparse arrays
+var sparseArr = [0, 1];
+sparseArr[10000] = 10000;
+Object.freeze(sparseArr);
+assertTrue(Object.isFrozen(sparseArr));