From 57bc570cc9f96721c9f7b36a04f4e1dde5459b31 Mon Sep 17 00:00:00 2001
From: Cameron Kaiser <classilla@floodgap.com>
Date: Sun, 28 Jan 2018 15:06:39 -0800
Subject: [PATCH] #471: speculative fix

---
 widget/cocoa/nsNativeThemeCocoa.mm | 1 +
 1 file changed, 1 insertion(+)

diff --git a/widget/cocoa/nsNativeThemeCocoa.mm b/widget/cocoa/nsNativeThemeCocoa.mm
index 146977d35..60c43c986 100644
--- a/widget/cocoa/nsNativeThemeCocoa.mm
+++ b/widget/cocoa/nsNativeThemeCocoa.mm
@@ -3391,6 +3391,7 @@ nsNativeThemeCocoa::DrawWidgetBackground(nsRenderingContext* aContext,
       // draw a focus ring
       if (eventState.HasState(NS_EVENT_STATE_FOCUS)) {
         NSGraphicsContext* savedContext = [NSGraphicsContext currentContext];
+        if (MOZ_UNLIKELY(!savedContext)) break; // speculative fix issue 471
         [NSGraphicsContext setCurrentContext:[NSGraphicsContext graphicsContextWithGraphicsPort:cgContext flipped:YES]];
         CGContextSaveGState(cgContext);
         NSSetFocusRingStyle(NSFocusRingOnly);