app/internal/wm: [Metal] don't limit CAMetalDrawable count

We shouldn't need more than 2 drawables, but changing the count from the
default of 3 introduces framerate lags in fullscreen mode.

This changes leaves the drawable count alone. No good deed goes
unpunished.

Signed-off-by: Elias Naur <mail@eliasnaur.com>

app/internal/wm/metal_darwin.go

@@ -38,10 +38,6 @@ static void setupLayer(CFTypeRef layerRef, CFTypeRef devRef) {
 			// Never let nextDrawable time out and return nil.
 			layer.allowsNextDrawableTimeout = NO;
 		}
-		if (@available(iOS 11.2, *)) {
-			// Minimize latency from input to window and save a bit of memory.
-			layer.maximumDrawableCount = 2;
-		}
 	}
 }