--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -220,17 +220,21 @@ pref("dom.gamepad.non_standard_events.en
 pref("dom.gamepad.non_standard_events.enabled", true);
 #endif
 pref("dom.gamepad.extensions.enabled", true);
 pref("dom.gamepad.haptic_feedback.enabled", true);
 
 // If this is true, TextEventDispatcher dispatches keydown and keyup events
 // even during composition (keypress events are never fired during composition
 // even if this is true).
+#ifdef EARLY_BETA_OR_EARLIER
+pref("dom.keyboardevent.dispatch_during_composition", true);
+#else
 pref("dom.keyboardevent.dispatch_during_composition", false);
+#endif
 
 // If this is true, TextEventDispatcher dispatches keypress event with setting
 // WidgetEvent::mFlags::mOnlySystemGroupDispatchInContent to true if it won't
 // cause inputting printable character.
 pref("dom.keyboardevent.keypress.dispatch_non_printable_keys_only_system_group_in_content", false);
 
 // Whether the WebMIDI API is enabled
 pref("dom.webmidi.enabled", false);

--- a/widget/TextEventDispatcher.cpp
+++ b/widget/TextEventDispatcher.cpp
@@ -35,17 +35,17 @@ TextEventDispatcher::TextEventDispatcher
 {
   MOZ_RELEASE_ASSERT(mWidget, "aWidget must not be nullptr");
 
   static bool sInitialized = false;
   if (!sInitialized) {
     Preferences::AddBoolVarCache(
       &sDispatchKeyEventsDuringComposition,
       "dom.keyboardevent.dispatch_during_composition",
-      false);
+      true);
     Preferences::AddBoolVarCache(
       &sDispatchKeyPressEventsOnlySystemGroupInContent,
       "dom.keyboardevent.keypress."
         "dispatch_non_printable_keys_only_system_group_in_content",
       false);
     sInitialized = true;
   }