Bug 1130746 - Always position window buttons at their default position in fullscreen mode. r=smichaud

widget/cocoa/nsCocoaWindow.mm

@@ -3325,7 +3325,7 @@ static const NSString* kStateShowsToolbarButton = @"showsToolbarButton";
 
 - (NSPoint)windowButtonsPositionWithDefaultPosition:(NSPoint)aDefaultPosition
 {
-  if ([self drawsContentsIntoWindowFrame]) {
+  if ([self drawsContentsIntoWindowFrame] && !([self styleMask] & NSFullScreenWindowMask)) {
     if (NSIsEmptyRect(mWindowButtonsRect)) {
       // Empty rect. Let's hide the buttons.
       // Position is in non-flipped window coordinates. Using frame's height