From 9dc89e761da4d282992f00cbe8aa214d5f60242d Mon Sep 17 00:00:00 2001
From: Mats Palmgren <mats@mozilla.com>
Date: Tue, 18 Apr 2017 22:35:05 +0200
Subject: [PATCH] Bug 1350925 part 2 - Assert that we're given clean
 ReflowOutput overflow areas in ReflowChild.  rs=dholbert

MozReview-Commit-ID: 1rRcC76jWxN
---
 layout/generic/nsContainerFrame.cpp | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/layout/generic/nsContainerFrame.cpp b/layout/generic/nsContainerFrame.cpp
index be579c802189..54a9ebbcfdb0 100644
--- a/layout/generic/nsContainerFrame.cpp
+++ b/layout/generic/nsContainerFrame.cpp
@@ -866,8 +866,8 @@ nsContainerFrame::ComputeAutoSize(nsRenderingContext* aRenderingContext,
 void
 nsContainerFrame::ReflowChild(nsIFrame*                aKidFrame,
                               nsPresContext*           aPresContext,
-                              ReflowOutput&     aDesiredSize,
-                              const ReflowInput& aReflowInput,
+                              ReflowOutput&            aDesiredSize,
+                              const ReflowInput&       aReflowInput,
                               const WritingMode&       aWM,
                               const LogicalPoint&      aPos,
                               const nsSize&            aContainerSize,
@@ -880,6 +880,9 @@ nsContainerFrame::ReflowChild(nsIFrame*                aKidFrame,
     NS_ASSERTION(aContainerSize.width != NS_UNCONSTRAINEDSIZE,
                  "ReflowChild with unconstrained container width!");
   }
+  MOZ_ASSERT(aDesiredSize.VisualOverflow() == nsRect(0,0,0,0) &&
+             aDesiredSize.ScrollableOverflow() == nsRect(0,0,0,0),
+             "please reset the overflow areas before calling ReflowChild");
 
   // Position the child frame and its view if requested.
   if (NS_FRAME_NO_MOVE_FRAME != (aFlags & NS_FRAME_NO_MOVE_FRAME)) {