From 1ccab328f9bc7e2952bbbfe7591804b6ce65ee9e Mon Sep 17 00:00:00 2001
From: Brandon Fairchild <csbit32@gmail.com>
Date: Thu, 31 Dec 2015 11:48:15 -0500
Subject: [PATCH] Support empty strings as the repeat argument (CreatePattern)

According to the third step in the specification [1], createPattern
should let the repetition argument be "repeat" when it is the empty
string.

The code in CanvasRenderingContext2D::CreatePattern did not implement
this step and instead threw a SyntaxError exception when an empty
string was supplied as the repetition argument.

Fixes #9079.

[1] https://html.spec.whatwg.org/multipage/#dom-context-2d-createpattern
---
 components/script/dom/canvasrenderingcontext2d.rs           | 6 +++++-
 .../fill-and-stroke-styles/2d.pattern.repeat.empty.html.ini | 5 -----
 .../fill-and-stroke-styles/2d.pattern.repeat.null.html.ini  | 5 -----
 3 files changed, 5 insertions(+), 11 deletions(-)
 delete mode 100644 tests/wpt/metadata/2dcontext/fill-and-stroke-styles/2d.pattern.repeat.empty.html.ini
 delete mode 100644 tests/wpt/metadata/2dcontext/fill-and-stroke-styles/2d.pattern.repeat.null.html.ini

diff --git a/components/script/dom/canvasrenderingcontext2d.rs b/components/script/dom/canvasrenderingcontext2d.rs
index 05a4b875852b..40cbb90a6a80 100644
--- a/components/script/dom/canvasrenderingcontext2d.rs
+++ b/components/script/dom/canvasrenderingcontext2d.rs
@@ -1147,7 +1147,7 @@ impl CanvasRenderingContext2DMethods for CanvasRenderingContext2D {
     // https://html.spec.whatwg.org/multipage/#dom-context-2d-createpattern
     fn CreatePattern(&self,
                      image: HTMLImageElementOrHTMLCanvasElementOrCanvasRenderingContext2D,
-                     repetition: DOMString)
+                     mut repetition: DOMString)
                      -> Fallible<Root<CanvasPattern>> {
         let (image_data, image_size) = match image {
             HTMLImageElementOrHTMLCanvasElementOrCanvasRenderingContext2D::eHTMLImageElement(ref image) => {
@@ -1169,6 +1169,10 @@ impl CanvasRenderingContext2DMethods for CanvasRenderingContext2D {
             }
         };
 
+        if repetition.is_empty() {
+            repetition.push_str("repeat");
+        }
+
         if let Ok(rep) = RepetitionStyle::from_str(&repetition) {
             Ok(CanvasPattern::new(self.global.root().r(),
                                   image_data,
diff --git a/tests/wpt/metadata/2dcontext/fill-and-stroke-styles/2d.pattern.repeat.empty.html.ini b/tests/wpt/metadata/2dcontext/fill-and-stroke-styles/2d.pattern.repeat.empty.html.ini
deleted file mode 100644
index 39ec1af8f9ce..000000000000
--- a/tests/wpt/metadata/2dcontext/fill-and-stroke-styles/2d.pattern.repeat.empty.html.ini
+++ /dev/null
@@ -1,5 +0,0 @@
-[2d.pattern.repeat.empty.html]
-  type: testharness
-  [Canvas test: 2d.pattern.repeat.empty]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata/2dcontext/fill-and-stroke-styles/2d.pattern.repeat.null.html.ini b/tests/wpt/metadata/2dcontext/fill-and-stroke-styles/2d.pattern.repeat.null.html.ini
deleted file mode 100644
index 1013179fffc0..000000000000
--- a/tests/wpt/metadata/2dcontext/fill-and-stroke-styles/2d.pattern.repeat.null.html.ini
+++ /dev/null
@@ -1,5 +0,0 @@
-[2d.pattern.repeat.null.html]
-  type: testharness
-  [Canvas test: 2d.pattern.repeat.null]
-    expected: FAIL
-