[gjs/mozjs78] Add 'Symbol.toStringTag' to GjsGlobal.

[Evan Welsh <ewlsh src gnome org>]

commit dccba25c1294760cd1b583c795845fe4c3a2caad
Author: Evan Welsh <noreply evanwelsh com>
Date:   Sun Jul 5 20:23:56 2020 -0500

    Add 'Symbol.toStringTag' to GjsGlobal.

 gjs/global.cpp | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)
---
diff --git a/gjs/global.cpp b/gjs/global.cpp
index f0c58b49..b25fe270 100644
--- a/gjs/global.cpp
+++ b/gjs/global.cpp
@@ -236,6 +236,9 @@ class GjsGlobal {
         &defaultclassops,
     };
 
+    static constexpr JSPropertySpec static_props[] = {
+        JS_STRING_SYM_PS(toStringTag, "GjsGlobal", JSPROP_READONLY), JS_PS_END};
+
     static constexpr JSFunctionSpec static_funcs[] = {
         JS_FN("log", gjs_log, 1, GJS_MODULE_PROP_FLAGS),
         JS_FN("logError", gjs_log_error, 2, GJS_MODULE_PROP_FLAGS),
@@ -279,7 +282,8 @@ class GjsGlobal {
         const GjsAtoms& atoms = GjsContextPrivate::atoms(cx);
         if (!JS_DefinePropertyById(cx, global, atoms.window(), global,
                                    JSPROP_READONLY | JSPROP_PERMANENT) ||
-            !JS_DefineFunctions(cx, global, GjsGlobal::static_funcs))
+            !JS_DefineFunctions(cx, global, GjsGlobal::static_funcs) ||
+            !JS_DefineProperties(cx, global, GjsGlobal::static_props))
             return false;
 
         JS::Realm* realm = JS::GetObjectRealmOrNull(global);
@@ -375,3 +379,4 @@ gjs_get_global_slot(JSContext    *cx,
 
 decltype(GjsGlobal::klass) constexpr GjsGlobal::klass;
 decltype(GjsGlobal::static_funcs) constexpr GjsGlobal::static_funcs;
+decltype(GjsGlobal::static_props) constexpr GjsGlobal::static_props;