Fix memory leak

src/lib/MarkdownView.vala

@@ -123,7 +123,6 @@ namespace GtkCommonMark {
 
         protected virtual void on_widget_embedded(MarkdownViewEmbeddedWidgetHost host, NodeInfo node) {
             host.set_available_width(calculate_embed_size(allocated_width));
-            available_size_for_embed_changed.connect(w => host.set_available_width(w));
             if(node.node_type == NodeType.IMAGE) {
                 widget_embedded(host, node.url, node.title);
             }
@@ -153,7 +152,15 @@ namespace GtkCommonMark {
             return width - tag_manager.page_margin * 2;
         }
 
-        private signal void available_size_for_embed_changed(int width);
+        private void available_size_for_embed_changed(int width) {
+            var children = observe_children();
+            for(uint i = 0; i < children.get_n_items(); i++){
+                var child = children.get_item(i);
+                if(child is MarkdownViewEmbeddedWidgetHost) {
+                    child.set_available_width(width);
+                }
+            }
+        }
 
     }