Codechange: [OSX] Remove old code that has no effect on current OSX versions.

src/video/cocoa/cocoa_ogl.mm

@@ -152,7 +152,6 @@ static bool _allowSoftware;
 {
 	if (self = [ super initWithFrame:frameRect ]) {
 		/* We manage our content updates ourselves. */
-		self.wantsBestResolutionOpenGLSurface = _allow_hidpi_window ? YES : NO;
 		self.layerContentsRedrawPolicy = NSViewLayerContentsRedrawOnSetNeedsDisplay;
 
 		/* Create backing layer. */

src/video/cocoa/cocoa_wnd.h

@@ -32,7 +32,6 @@ extern NSString *OTTDMainLaunchGameEngine;
 @interface OTTD_CocoaWindow : NSWindow
 - (instancetype)initWithContentRect:(NSRect)contentRect styleMask:(NSUInteger)styleMask backing:(NSBackingStoreType)backingType defer:(BOOL)flag driver:(VideoDriver_Cocoa *)drv;
 
-- (void)display;
 - (void)setFrame:(NSRect)frameRect display:(BOOL)flag;
 @end
 

src/video/cocoa/cocoa_wnd.mm

@@ -405,23 +405,6 @@ void CocoaDialog(const char *title, const char *message, const char *buttonLabel
 	return self;
 }
 
-/**
- * This method fires just before the window deminaturizes from the Dock.
- * We'll save the current visible surface, let the window manager redraw any
- * UI elements, and restore the surface. This way, no expose event
- * is required, and the deminiaturize works perfectly.
- */
-- (void)display
-{
-	/* save current visible surface */
-	[ self cacheImageInRect:[ driver->cocoaview frame ] ];
-
-	/* let the window manager redraw controls, border, etc */
-	[ super display ];
-
-	/* restore visible surface */
-	[ self restoreCachedImage ];
-}
 /**
  * Define the rectangle we draw our window in
  */