cssnode: Redo GTK_DEBUG=no-css-cache

Previously this setting would just invalidate the whole CSS tree and
thereby hopefully avoid all cache usage.

Now, we actually don't cause extra invalidations anymore, but instead
avoid ever inserting anything into the cache when this setting is set.

gtk/gtkcssnode.c

@@ -22,7 +22,6 @@
 #include "gtkcssanimatedstyleprivate.h"
 #include "gtkcsssectionprivate.h"
 #include "gtkcssstylepropertyprivate.h"
-#include "gtkdebug.h"
 #include "gtkintl.h"
 #include "gtkmarshalers.h"
 #include "gtksettingsprivate.h"
@@ -1372,23 +1371,6 @@ gtk_css_node_validate_internal (GtkCssNode *cssnode,
 {
   GtkCssNode *child;
 
-  /* If you run your application with
-   *   GTK_DEBUG=no-css-cache
-   * every invalidation will purge the cache and completely query
-   * everything anew form the cache. This is slow (in particular
-   * when animating), but useful for figuring out bugs.
-   *
-   * We achieve that by pretending that everything that could have
-   * changed has and so we of course totally need to redo everything.
-   *
-   * Note that this also completely revalidates child widgets all
-   * the time.
-   */
-#ifdef G_ENABLE_DEBUG
-  if (GTK_DEBUG_CHECK (NO_CSS_CACHE))
-    cssnode->pending_changes |= GTK_CSS_CHANGE_ANY;
-#endif
-
   if (!cssnode->invalid)
     return;
 

gtk/gtkcssnodestylecache.c

@@ -19,6 +19,7 @@
 
 #include "gtkcssnodestylecacheprivate.h"
 
+#include "gtkdebug.h"
 #include "gtkcssstaticstyleprivate.h"
 
 struct _GtkCssNodeStyleCache {
@@ -78,6 +79,18 @@ may_be_stored_in_cache (GtkCssStyle *style)
 {
   GtkCssChange change;
 
+  /* If you run your application with
+   *   GTK_DEBUG=no-css-cache
+   * no caching will happen. This is slow (in particular
+   * when animating), but useful for figuring out bugs.
+   *
+   * We achieve that by disallowing any inserts into caches here.
+   */
+#ifdef G_ENABLE_DEBUG
+  if (GTK_DEBUG_CHECK (NO_CSS_CACHE))
+    return FALSE;
+#endif
+
   if (!GTK_IS_CSS_STATIC_STYLE (style))
     return FALSE;