spring: Tweak the window fade-in spring to not overshoot

The fade animation overshoots and rings for a bit dipping back into
slightly transparent.  Bug 61675 was right.

https://bugs.freedesktop.org/show_bug.cgi?id=61675
diff --git a/src/shell.c b/src/shell.c
index a3b1b1f..b033529 100644
--- a/src/shell.c
+++ b/src/shell.c
@@ -3135,12 +3135,11 @@
 	}
 
 	if (shell->fade.animation)
-		weston_fade_update(shell->fade.animation,
-				   shell->fade.surface->alpha, tint, 30.0);
+		weston_fade_update(shell->fade.animation, tint);
 	else
 		shell->fade.animation =
 			weston_fade_run(shell->fade.surface,
-					1.0 - tint, tint, 30.0,
+					1.0 - tint, tint, 300.0,
 					shell_fade_done, shell);
 }
 
@@ -3457,7 +3456,7 @@
 	{
 		switch (shell->win_animation_type) {
 		case ANIMATION_FADE:
-			weston_fade_run(surface, 0.0, 1.0, 200.0, NULL, NULL);
+			weston_fade_run(surface, 0.0, 1.0, 300.0, NULL, NULL);
 			break;
 		case ANIMATION_ZOOM:
 			weston_zoom_run(surface, 0.8, 1.0, NULL, NULL);