[mutter] MetaTextureTower: actually mark revalidated levels as valid

[Owen Taylor <otaylor src gnome org>]

commit 249468bbea47a24e31945452c13414f82d40c105
Author: Owen W. Taylor <otaylor fishsoup net>
Date:   Thu Aug 7 10:21:51 2014 +0200

    MetaTextureTower: actually mark revalidated levels as valid
    
    We were never actually clearing the invalid area on the smaller levels
    of the texture tower, so we recomputed those levels every time.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=734400

 src/compositor/meta-texture-tower.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/src/compositor/meta-texture-tower.c b/src/compositor/meta-texture-tower.c
index 5d82add..80675c2 100644
--- a/src/compositor/meta-texture-tower.c
+++ b/src/compositor/meta-texture-tower.c
@@ -432,6 +432,9 @@ texture_tower_revalidate (MetaTextureTower *tower,
                           int               level)
 {
   texture_tower_revalidate_fbo (tower, level);
+
+  tower->invalid[level].x1 = tower->invalid[level].x2 = 0;
+  tower->invalid[level].y1 = tower->invalid[level].y2 = 0;
 }
 
 /**