From c2b844077e719355214dcf7f1ab90f811cfac99c Mon Sep 17 00:00:00 2001
From: wolfbeast <mcwerewolf@wolfbeast.com>
Date: Wed, 14 Aug 2019 15:09:34 +0200
Subject: [PATCH] Issue #438: Check for non-rectilinear transforms

---
 layout/svg/nsSVGOuterSVGFrame.cpp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/layout/svg/nsSVGOuterSVGFrame.cpp b/layout/svg/nsSVGOuterSVGFrame.cpp
index e1b97bb40b..434676010d 100644
--- a/layout/svg/nsSVGOuterSVGFrame.cpp
+++ b/layout/svg/nsSVGOuterSVGFrame.cpp
@@ -1006,6 +1006,9 @@ nsSVGOuterSVGAnonChildFrame::IsSVGTransformed(Matrix* aOwnTransform,
     if (ownMatrix.HasNonTranslation()) {
       // Note: viewBox, currentScale and currentTranslate should only
       // produce a rectilinear transform.
+      MOZ_ASSERT(ownMatrix.IsRectilinear(),
+                 "Non-rectilinear transform will break the following logic");
+      
       // The nsDisplayTransform code will apply this transform to our frame,
       // including to our frame position.  We don't want our frame position to
       // be scaled though, so we need to correct for that in the transform.