[mutter] shaped-texture: Add checks to viewport reset functions

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 96f7bf28f15f0a43559d5197be773d125c62f494
Author: Robert Mader <robert mader posteo de>
Date:   Fri Mar 29 01:56:34 2019 +0100

    shaped-texture: Add checks to viewport reset functions
    
    The set and reset functions are unconditionally called on every
    commit. Add missings checks to the reset functions to bail out if
    nothing changed.
    
    https://gitlab.gnome.org/GNOME/mutter/merge_requests/504

 src/compositor/meta-shaped-texture.c | 6 ++++++
 1 file changed, 6 insertions(+)
---
diff --git a/src/compositor/meta-shaped-texture.c b/src/compositor/meta-shaped-texture.c
index d64e214e5..777e68632 100644
--- a/src/compositor/meta-shaped-texture.c
+++ b/src/compositor/meta-shaped-texture.c
@@ -1214,6 +1214,9 @@ meta_shaped_texture_set_viewport_src_rect (MetaShapedTexture *stex,
 void
 meta_shaped_texture_reset_viewport_src_rect (MetaShapedTexture *stex)
 {
+  if (!stex->has_viewport_src_rect)
+    return;
+
   stex->has_viewport_src_rect = FALSE;
   invalidate_size (stex);
 }
@@ -1237,6 +1240,9 @@ meta_shaped_texture_set_viewport_dst_size (MetaShapedTexture *stex,
 void
 meta_shaped_texture_reset_viewport_dst_size (MetaShapedTexture *stex)
 {
+  if (!stex->has_viewport_dst_size)
+    return;
+
   stex->has_viewport_dst_size = FALSE;
   invalidate_size (stex);
 }