Add missing parentheses that resulted in repainting issues in the audio display with inactive lines disabled

Originally committed to SVN as r6281.

aegisub/src/audio_timing_dialogue.cpp

@@ -483,7 +483,7 @@ void AudioTimingControllerDialogue::Revert()
 			timing_modified = false;
 			AnnounceUpdatedPrimaryRange();
 			if (inactive_line_mode->GetInt() == 0)
-				AnnounceUpdatedStyleRanges;
+				AnnounceUpdatedStyleRanges();
 		}
 	}
 	RegenerateInactiveLines();