css: Don't keep around linear selectors

Now we use the selector tree everywhere, so there is no need to
keep around the linear selectors unless we're using them to
verify the tree correctness, so free them.

gtk/gtkcssprovider.c

@@ -2430,6 +2430,18 @@ gtk_css_provider_postprocess (GtkCssProvider *css_provider)
 
   priv->tree = _gtk_css_selector_tree_builder_build (builder);
   _gtk_css_selector_tree_builder_free (builder);
+
+#ifndef VERIFY_TREE
+  for (i = 0; i < priv->rulesets->len; i++)
+    {
+      GtkCssRuleset *ruleset;
+
+      ruleset = &g_array_index (priv->rulesets, GtkCssRuleset, i);
+
+      _gtk_css_selector_free (ruleset->selector);
+      ruleset->selector = NULL;
+    }
+#endif
 }
 
 static gboolean