Fix #8808: [OSX, OpenGL] Crash on switching blitters due to double-mapping the video buffer.

src/video/cocoa/cocoa_v.mm

@@ -213,7 +213,7 @@ bool VideoDriver_Cocoa::ToggleFullscreen(bool full_screen)
  */
 bool VideoDriver_Cocoa::AfterBlitterChange()
 {
-	this->ChangeResolution(_cur_resolution.width, _cur_resolution.height);
+	this->AllocateBackingStore(true);
 	return true;
 }
 
@@ -224,7 +224,7 @@ void VideoDriver_Cocoa::EditBoxLostFocus()
 {
 	[ [ this->cocoaview inputContext ] discardMarkedText ];
 	/* Clear any marked string from the current edit box. */
-	HandleTextInput(NULL, true);
+	HandleTextInput(nullptr, true);
 }
 
 /**