Adding a unit test to verify fix to +[CPDictionary dictionaryWithJSObject:(JSObject)object recursively:(BOOL)recursively]

Tests/Foundation/CPDictionaryTest.j

@@ -16,6 +16,12 @@
 
     string_dict = [[CPDictionary alloc] initWithObjects:[@"1", @"2"] forKeys:[@"key1", @"key2"]];
     json_dict = [CPDictionary dictionaryWithJSObject:json recursively:YES];
+    
+    json_with_nulls = {
+        "key1": ['1', '2', '3'],
+        "key2": "This is a string",
+        "key3": null
+    }
 }
 
 - (void)testInitWithDictionary
@@ -58,6 +64,14 @@
     [self assert:[[dict objectForKey:@"key3"] count] equals:1];
 }
 
+- (void)testDictionaryWithJSObjectRecursiveWithNull
+{
+    var dict = [CPDictionary dictionaryWithJSObject:json_with_nulls recursively:YES];
+    [self assert:2 equals:[dict count]];
+    [self assert:[@"key1", @"key2"] equals:[dict allKeys]];
+    [self assert:[dict objectForKey:@"key3"] equals:nil];
+}
+
 - (void)testDictionaryWithJSObjectNonRecursive
 {
     var non_recursive_dict = [CPDictionary dictionaryWithJSObject:json recursively:NO];