[gjs/gnome-3-28] Export GObject static class properties.

[Philip Chimento <pchimento src gnome org>]

commit 0abb94158e84ac209d3c9361c9be48f6b721eb54
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 741a9f39..bf1ae97a 100644
--- a/modules/overrides/GObject.js
+++ b/modules/overrides/GObject.js
@@ -441,6 +441,14 @@ function _init() {
     GObject._children = _children;
     GObject._internalChildren = _internalChildren;
 
+    // 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
     this.AccumulatorType = {
         NONE: 0,