Bug 1364843 - Allow MOZ_GTK_HEADER_BAR* widget creation, r=jhorak

Based on patch by Andrew Comminos [:acomminos] <andrew@comminos.com>

MozReview-Commit-ID: 18U3GBrTyVW

--HG--
extra : rebase_source : 7a203d5c4d1856d24f08c2ea42ad4519d283ab73

widget/gtk/WidgetStyleCache.cpp

@@ -672,6 +672,13 @@ CreateWidget(WidgetNodeType aWidgetType)
       return CreateComboBoxEntryButtonWidget();
     case MOZ_GTK_COMBOBOX_ENTRY_ARROW:
       return CreateComboBoxEntryArrowWidget();
+    case MOZ_GTK_HEADER_BAR:
+    case MOZ_GTK_HEADER_BAR_MAXIMIZED:
+      return CreateHeaderBar(aWidgetType);
+    case MOZ_GTK_HEADER_BAR_BUTTON_CLOSE:
+    case MOZ_GTK_HEADER_BAR_BUTTON_MINIMIZE:
+    case MOZ_GTK_HEADER_BAR_BUTTON_MAXIMIZE:
+      return CreateHeaderBarButton(aWidgetType);
     default:
       /* Not implemented */
       return nullptr;