stylecontext: Move property cache

... from per style data to only existing once per style context. This is
technically an API break because it no longer allows getting different
style properties between save()/restore() pairs, but I don't think this
was ever intended to work that way, as the style property API was to be
used and is used via gtk_widget_get_style().

And it simplifies code a lot.

gtk/gtkstylecontext.c

@@ -260,7 +260,6 @@ struct GtkStyleInfo
 struct StyleData
 {
   GtkCssComputedValues *store;
-  GArray *property_cache;
   guint ref_count;
 };
 
@@ -276,6 +275,7 @@ struct _GtkStyleContextPrivate
   GtkWidgetPath *widget_path;
   GHashTable *style_data;
   GtkStyleInfo *info;
+  GArray *property_cache;
   gint scale;
 
   guint frame_clock_update_id;
@@ -403,23 +403,20 @@ style_data_new (void)
 }
 
 static void
-clear_property_cache (StyleData *data)
+gtk_style_context_clear_property_cache (GtkStyleContext *context)
 {
+  GtkStyleContextPrivate *priv = context->priv;
   guint i;
 
-  if (!data->property_cache)
-    return;
-
-  for (i = 0; i < data->property_cache->len; i++)
+  for (i = 0; i < priv->property_cache->len; i++)
     {
-      PropertyValue *node = &g_array_index (data->property_cache, PropertyValue, i);
+      PropertyValue *node = &g_array_index (priv->property_cache, PropertyValue, i);
 
       g_param_spec_unref (node->pspec);
       g_value_unset (&node->value);
     }
 
-  g_array_free (data->property_cache, TRUE);
-  data->property_cache = NULL;
+  g_array_set_size (priv->property_cache, 0);
 }
 
 static StyleData *
@@ -439,7 +436,6 @@ style_data_unref (StyleData *data)
     return;
 
   g_object_unref (data->store);
-  clear_property_cache (data);
 
   g_slice_free (StyleData, data);
 }
@@ -640,6 +636,8 @@ gtk_style_context_init (GtkStyleContext *style_context)
   priv->info = style_info_new ();
   priv->info->state_flags = GTK_STATE_FLAG_DIR_LTR;
 
+  priv->property_cache = g_array_new (FALSE, FALSE, sizeof (PropertyValue));
+
   gtk_style_context_set_cascade (style_context,
                                  _gtk_settings_get_style_cascade (gtk_settings_get_for_screen (priv->screen)));
 }
@@ -775,6 +773,9 @@ gtk_style_context_finalize (GObject *object)
   while (priv->info)
     priv->info = style_info_pop (priv->info);
 
+  gtk_style_context_clear_property_cache (style_context);
+  g_array_free (priv->property_cache, TRUE);
+
   G_OBJECT_CLASS (gtk_style_context_parent_class)->finalize (object);
 }
 
@@ -2200,35 +2201,27 @@ _gtk_style_context_peek_style_property (GtkStyleContext *context,
 {
   GtkStyleContextPrivate *priv;
   PropertyValue *pcache, key = { 0 };
-  StyleData *data;
   guint i;
 
   priv = context->priv;
 
-  data = style_data_lookup (context);
-
   key.widget_type = widget_type;
   key.pspec = pspec;
 
   /* need value cache array */
-  if (!data->property_cache)
-    data->property_cache = g_array_new (FALSE, FALSE, sizeof (PropertyValue));
-  else
-    {
-      pcache = bsearch (&key,
-                        data->property_cache->data, data->property_cache->len,
-                        sizeof (PropertyValue), style_property_values_cmp);
-      if (pcache)
-        return &pcache->value;
-    }
+  pcache = bsearch (&key,
+                    priv->property_cache->data, priv->property_cache->len,
+                    sizeof (PropertyValue), style_property_values_cmp);
+  if (pcache)
+    return &pcache->value;
 
   i = 0;
-  while (i < data->property_cache->len &&
-         style_property_values_cmp (&key, &g_array_index (data->property_cache, PropertyValue, i)) >= 0)
+  while (i < priv->property_cache->len &&
+         style_property_values_cmp (&key, &g_array_index (priv->property_cache, PropertyValue, i)) >= 0)
     i++;
 
-  g_array_insert_val (data->property_cache, i, key);
-  pcache = &g_array_index (data->property_cache, PropertyValue, i);
+  g_array_insert_val (priv->property_cache, i, key);
+  pcache = &g_array_index (priv->property_cache, PropertyValue, i);
 
   /* cache miss, initialize value type, then set contents */
   g_param_spec_ref (pcache->pspec);
@@ -2996,6 +2989,8 @@ gtk_style_context_clear_cache (GtkStyleContext *context)
       style_info_set_data (info, NULL);
     }
   g_hash_table_remove_all (priv->style_data);
+
+  gtk_style_context_clear_property_cache (context);
 }
 
 static void
@@ -3025,6 +3020,8 @@ gtk_style_context_update_cache (GtkStyleContext  *context,
 
       _gtk_bitmask_free (changes);
     }
+
+  gtk_style_context_clear_property_cache (context);
 }
 
 static void