[gnome-builder] editor-settings: Fix potential unref of last style scheme reference.

[Christian Hergert <chergert src gnome org>]

commit 0b4c6f63a37c0843a0e622039b0cb0d7f0819d28
Author: Christian Hergert <christian hergert me>
Date:   Mon Sep 29 01:53:13 2014 -0700

    editor-settings: Fix potential unref of last style scheme reference.
    
    This could happen if setting the value to the same style scheme as
    previously set (if the refcount was at 1).

 src/editor/gb-editor-settings.c |   13 ++++++++++---
 1 files changed, 10 insertions(+), 3 deletions(-)
---
diff --git a/src/editor/gb-editor-settings.c b/src/editor/gb-editor-settings.c
index e4af2de..261d929 100644
--- a/src/editor/gb-editor-settings.c
+++ b/src/editor/gb-editor-settings.c
@@ -87,10 +87,17 @@ gb_editor_settings_set_style_scheme (GbEditorSettings     *settings,
                                      GtkSourceStyleScheme *style_scheme)
 {
   g_return_if_fail (GB_IS_EDITOR_SETTINGS (settings));
-  g_return_if_fail (GTK_SOURCE_IS_STYLE_SCHEME (style_scheme));
+  g_return_if_fail (!style_scheme || GTK_SOURCE_IS_STYLE_SCHEME (style_scheme));
+
+  if (style_scheme == settings->priv->style_scheme)
+    return;
+
+  if (settings->priv->style_scheme)
+    g_clear_object (&settings->priv->style_scheme);
+
+  if (style_scheme)
+    settings->priv->style_scheme = g_object_ref (style_scheme);
 
-  g_clear_object (&settings->priv->style_scheme);
-  settings->priv->style_scheme = g_object_ref (style_scheme);
   g_object_notify_by_pspec (G_OBJECT (settings),
                             gParamSpecs[PROP_STYLE_SCHEME]);
 }