[gnome-builder] editor: fix new-button icon name

[Christian Hergert <chergert src gnome org>]

commit 3b9bd6689c46e727af619d8225007f24f4b0eb8a
Author: Christian Hergert <chergert redhat com>
Date:   Mon Jul 10 14:58:29 2017 -0700

    editor: fix new-button icon name

 libide/editor/ide-editor-workbench-addin.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/libide/editor/ide-editor-workbench-addin.c b/libide/editor/ide-editor-workbench-addin.c
index 154ee43..abccb82 100644
--- a/libide/editor/ide-editor-workbench-addin.c
+++ b/libide/editor/ide-editor-workbench-addin.c
@@ -173,7 +173,7 @@ ide_editor_workbench_addin_add_buttons (IdeEditorWorkbenchAddin *self,
   gtk_container_add (GTK_CONTAINER (self->panels_box), button);
 
   self->new_button = g_object_new (DZL_TYPE_MENU_BUTTON,
-                                   "icon-name", "document-new-symbolic",
+                                   "icon-name", "document-open-symbolic",
                                    "focus-on-click", FALSE,
                                    "show-arrow", TRUE,
                                    "show-icons", FALSE,