Remove a FIXME from SDL2_FNAPlatform.

I'm not really convinced this was ever a bug anymore...

src/FNAPlatform/SDL2_FNAPlatform.cs

@@ -572,13 +572,7 @@ public static Rectangle GetWindowBounds(IntPtr window)
 			Rectangle result;
 			if ((SDL.SDL_GetWindowFlags(window) & (uint) SDL.SDL_WindowFlags.SDL_WINDOW_FULLSCREEN) != 0)
 			{
-				/* FIXME: SDL2 bug!
-				 * SDL's a little weird about SDL_GetWindowSize.
-				 * If you call it early enough (for example,
-				 * Game.Initialize()), it reports outdated ints.
-				 * So you know what, let's just use this.
-				 * -flibit
-				 */
+				/* It's easier/safer to just use the display mode here */
 				SDL.SDL_DisplayMode mode;
 				SDL.SDL_GetCurrentDisplayMode(
 					SDL.SDL_GetWindowDisplayIndex(