Move CPWindow+CPDraggingAdditions to CPWindow to avoid circular dependency

AppKit/CPDragServer.j

@@ -477,35 +477,3 @@ var CPDraggingSource_draggedImage_movedTo_          = 1 << 0,
 }
 
 @end
-
-@implementation CPWindow (CPDraggingAdditions)
-
-/* @ignore */
-- (id)_dragHitTest:(CGPoint)aPoint pasteboard:(CPPasteboard)aPasteboard
-{
-    // If none of our views or ourselves has registered for drag events...
-    if (!_inclusiveRegisteredDraggedTypes)
-        return nil;
-
-// We don't need to do this because the only place this gets called
-// -_dragHitTest: in CPPlatformWindow does this already. Perhaps to
-// be safe?
-//    if (![self containsPoint:aPoint])
-//        return nil;
-
-    var adjustedPoint = [self convertPlatformWindowToBase:aPoint],
-        hitView = [_windowView hitTest:adjustedPoint];
-
-    while (hitView && ![aPasteboard availableTypeFromArray:[hitView registeredDraggedTypes]])
-        hitView = [hitView superview];
-
-    if (hitView)
-        return hitView;
-
-    if ([aPasteboard availableTypeFromArray:[self registeredDraggedTypes]])
-        return self;
-
-    return nil;
-}
-
-@end

AppKit/CPWindow/CPWindow.j

@@ -3425,6 +3425,39 @@ var interpolate = function(fromValue, toValue, progress)
 
 @end
 
+
+@implementation CPWindow (CPDraggingAdditions)
+
+/* @ignore */
+- (id)_dragHitTest:(CGPoint)aPoint pasteboard:(CPPasteboard)aPasteboard
+{
+    // If none of our views or ourselves has registered for drag events...
+    if (!_inclusiveRegisteredDraggedTypes)
+        return nil;
+
+// We don't need to do this because the only place this gets called
+// -_dragHitTest: in CPPlatformWindow does this already. Perhaps to
+// be safe?
+//    if (![self containsPoint:aPoint])
+//        return nil;
+
+    var adjustedPoint = [self convertPlatformWindowToBase:aPoint],
+        hitView = [_windowView hitTest:adjustedPoint];
+
+    while (hitView && ![aPasteboard availableTypeFromArray:[hitView registeredDraggedTypes]])
+        hitView = [hitView superview];
+
+    if (hitView)
+        return hitView;
+
+    if ([aPasteboard availableTypeFromArray:[self registeredDraggedTypes]])
+        return self;
+
+    return nil;
+}
+
+@end
+
 function _CPWindowFullPlatformWindowSessionMake(aWindowView, aContentRect, hasShadow, aLevel)
 {
     return { windowView:aWindowView, contentRect:aContentRect, hasShadow:hasShadow, level:aLevel };