Fixes #829. Improve - CPView removeFromSuperview performance.

In the modified test described in #829 performance improves by at least 30% and that's with a significant addSubview: component diluting the test.

This change should improve outline and table view performance.

AppKit/CPView.j

@@ -565,10 +565,10 @@ var CPViewFlags                     = { },
 
     [_superview willRemoveSubview:self];
 
-    [_superview._subviews removeObject:self];
+    [_superview._subviews removeObjectIdenticalTo:self];
 
 #if PLATFORM(DOM)
-        CPDOMDisplayServerRemoveChild(_superview._DOMElement, _DOMElement);
+    CPDOMDisplayServerRemoveChild(_superview._DOMElement, _DOMElement);
 #endif
     _superview = nil;