From 7d48c9fa90d3dfa2cc2f0ff47c8677912e9cd313 Mon Sep 17 00:00:00 2001
From: Xidorn Quan <me@upsuper.org>
Date: Wed, 24 May 2017 21:53:52 +1000
Subject: [PATCH] Only allow color value at the last element.

---
 .../style/properties/shorthand/background.mako.rs   | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/components/style/properties/shorthand/background.mako.rs b/components/style/properties/shorthand/background.mako.rs
index 58f0361cffa..5a7747cf3fb 100644
--- a/components/style/properties/shorthand/background.mako.rs
+++ b/components/style/properties/shorthand/background.mako.rs
@@ -39,17 +39,20 @@
             let mut background_${name} = background_${name}::SpecifiedValue(Vec::new());
         % endfor
         try!(input.parse_comma_separated(|input| {
+            // background-color can only be in the last element, so if it
+            // is parsed anywhere before, the value is invalid.
+            if background_color.is_some() {
+                return Err(());
+            }
+
             % for name in "image position repeat size attachment origin clip".split():
                 let mut ${name} = None;
             % endfor
             loop {
-                if let Ok(value) = input.try(|i| CSSColor::parse(context, i)) {
-                    if background_color.is_none() {
+                if background_color.is_none() {
+                    if let Ok(value) = input.try(|i| CSSColor::parse(context, i)) {
                         background_color = Some(value);
                         continue
-                    } else {
-                        // color can only be the last element
-                        return Err(())
                     }
                 }
                 if position.is_none() {