From 4666f0be0ec99f848fe979ce28022b82c7297dcc Mon Sep 17 00:00:00 2001
From: Daniel Freedman <dfreedm@google.com>
Date: Wed, 20 Sep 2017 15:45:13 -0700
Subject: [PATCH] Fix broken tests related to Edge 15 bugs with CSS Custom
 properties

Port webcomponents/shadycss#120 to 1.x
---
 src/lib/settings.html | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/lib/settings.html b/src/lib/settings.html
index 41f138add1..e0b433757c 100644
--- a/src/lib/settings.html
+++ b/src/lib/settings.html
@@ -48,8 +48,10 @@
 
       // chrome 49 has semi-working css vars, check if box-shadow works
       // safari 9.1 has a recalc bug: https://bugs.webkit.org/show_bug.cgi?id=155782
+      // Edge 15: custom properties used in ::before and ::after will also be used in the parent element
+      // https://developer.microsoft.com/en-us/microsoft-edge/platform/issues/12414257/
       settings.hasNativeCSSProperties =
-        (!navigator.userAgent.match('AppleWebKit/601') && window.CSS
+        (!navigator.userAgent.match(/AppleWebKit\/601|Edge\/15/) && window.CSS
         && CSS.supports && CSS.supports('box-shadow', '0 0 0 var(--foo)'));
 
       settings.useNativeCSSProperties = settings.hasNativeCSSProperties &&