[gjs/mozjs91] engine: Enable private fields and methods

[Philip Chimento <pchimento src gnome org>]

commit c6cbb4ec8661b99f5fb3a89dbf15d535da5b62a0
Author: Philip Chimento <philip chimento gmail com>
Date:   Mon Oct 11 11:37:23 2021 -0700

    engine: Enable private fields and methods
    
    These do not yet work with GObject classes (see GNOME/gjs#331) but it
    seems OK to enable them for non-GObject classes in the meantime,
    especially since we already have public fields enabled but not yet
    working with GObject classes.

 gjs/engine.cpp | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)
---
diff --git a/gjs/engine.cpp b/gjs/engine.cpp
index 540c8ee6..1da606b8 100644
--- a/gjs/engine.cpp
+++ b/gjs/engine.cpp
@@ -167,7 +167,11 @@ JSContext* gjs_create_js_context(GjsContextPrivate* uninitialized_gjs) {
     if (enable_jit) {
         gjs_debug(GJS_DEBUG_CONTEXT, "Enabling JIT");
     }
-    JS::ContextOptionsRef(cx).setAsmJS(enable_jit).setTopLevelAwait(false);
+    JS::ContextOptionsRef(cx)
+        .setAsmJS(enable_jit)
+        .setTopLevelAwait(false)
+        .setPrivateClassFields(true)
+        .setPrivateClassMethods(true);
 
     uint32_t value = enable_jit ? 1 : 0;