widget: Drop the ::size-allocate signal

This signal is mainly used for bad things, and we
don't want to emit signals during layout if we can
avoid it.

If you are subclassing, you should either use a
layout manager or override the size_allocate vfunc.

If you are using a GtkDrawingArea or GtkGLArea,
use their ::resize signals to learn about size
changes.

Fixes: #2705

gtk/gtkwidget.c

@@ -1485,28 +1485,6 @@ gtk_widget_class_init (GtkWidgetClass *klass)
                   NULL,
 		  G_TYPE_NONE, 0);
 
-  /**
-   * GtkWidget::size-allocate:
-   * @widget: the object which received the signal.
-   * @width: the content width of the widget
-   * @height: the content height of the widget
-   * @baseline: the baseline
-   */
-  widget_signals[SIZE_ALLOCATE] =
-    g_signal_new (I_("size-allocate"),
-		  G_TYPE_FROM_CLASS (gobject_class),
-		  G_SIGNAL_RUN_FIRST,
-		  G_STRUCT_OFFSET (GtkWidgetClass, size_allocate),
-		  NULL, NULL,
-                  _gtk_marshal_VOID__INT_INT_INT,
-		  G_TYPE_NONE, 3,
-                  G_TYPE_INT,
-                  G_TYPE_INT,
-                  G_TYPE_INT);
-  g_signal_set_va_marshaller (widget_signals[SIZE_ALLOCATE],
-                              G_TYPE_FROM_CLASS (gobject_class),
-                              _gtk_marshal_VOID__INT_INT_INTv);
-
   /**
    * GtkWidget::state-flags-changed:
    * @widget: the object which received the signal.
@@ -4095,16 +4073,10 @@ gtk_widget_allocate (GtkWidget    *widget,
     }
   else
     {
-      if (g_signal_has_handler_pending (widget, widget_signals[SIZE_ALLOCATE], 0, FALSE))
-        g_signal_emit (widget, widget_signals[SIZE_ALLOCATE], 0,
-                       priv->width,
-                       priv->height,
-                       baseline);
-      else
-        GTK_WIDGET_GET_CLASS (widget)->size_allocate (widget,
-                                                      priv->width,
-                                                      priv->height,
-                                                      baseline);
+      GTK_WIDGET_GET_CLASS (widget)->size_allocate (widget,
+                                                    priv->width,
+                                                    priv->height,
+                                                    baseline);
     }
 
   /* Size allocation is god... after consulting god, no further requests or allocations are needed */