[gjs: 3/4] Export GObject static class properties.

[Philip Chimento <pchimento src gnome org>]

commit c1d23050163e5bd5608660b1e6fa597e4b0adffb
Author: rockon999 <rockon999 users noreply github com>
Date:   Fri Jul 20 10:48:06 2018 -0500

    Export GObject static class properties.

 modules/overrides/GObject.js | 8 ++++++++
 1 file changed, 8 insertions(+)
---
diff --git a/modules/overrides/GObject.js b/modules/overrides/GObject.js
index 7b3d4f72..167942ca 100644
--- a/modules/overrides/GObject.js
+++ b/modules/overrides/GObject.js
@@ -444,6 +444,14 @@ function _init() {
     GObject.__gtkChildren__ = _gtkChildren;
     GObject.__gtkInternalChildren__ = _gtkInternalChildren;
 
+    // Expose GObject static properties for ES6 classes
+
+    GObject.GTypeName = GTypeName;
+    GObject.requires = requires;
+    GObject.interfaces = interfaces;
+    GObject.properties = properties;
+    GObject.signals = signals;
+
     // fake enum for signal accumulators, keep in sync with gi/object.c
     GObject.AccumulatorType = {
         NONE: 0,