From 3c3311b16a0a1f0c84d02ff10283fb0800529184 Mon Sep 17 00:00:00 2001
From: Josh Matthews <josh@joshmatthews.net>
Date: Thu, 13 Apr 2017 16:02:17 +1000
Subject: [PATCH] Allow loading multiple stylesheets for the same link element.

---
 components/script/dom/htmllinkelement.rs      |  6 ++-
 components/script/stylesheet_loader.rs        |  5 +--
 tests/wpt/metadata/MANIFEST.json              | 43 +++++++++++++++++++
 .../the-link-element/resources/bad.css        |  4 ++
 .../the-link-element/resources/good.css       |  3 ++
 .../stylesheet-change-href-ref.html           |  8 ++++
 .../stylesheet-change-href.html               | 13 ++++++
 7 files changed, 76 insertions(+), 6 deletions(-)
 create mode 100644 tests/wpt/web-platform-tests/html/semantics/document-metadata/the-link-element/resources/bad.css
 create mode 100644 tests/wpt/web-platform-tests/html/semantics/document-metadata/the-link-element/resources/good.css
 create mode 100644 tests/wpt/web-platform-tests/html/semantics/document-metadata/the-link-element/stylesheet-change-href-ref.html
 create mode 100644 tests/wpt/web-platform-tests/html/semantics/document-metadata/the-link-element/stylesheet-change-href.html

diff --git a/components/script/dom/htmllinkelement.rs b/components/script/dom/htmllinkelement.rs
index d29a94a11f0..bb7fe85366d 100644
--- a/components/script/dom/htmllinkelement.rs
+++ b/components/script/dom/htmllinkelement.rs
@@ -24,6 +24,7 @@ use dom::virtualmethods::VirtualMethods;
 use dom_struct::dom_struct;
 use html5ever_atoms::LocalName;
 use net_traits::ReferrerPolicy;
+use script_layout_interface::message::Msg;
 use script_traits::{MozBrowserEvent, ScriptMsg as ConstellationMsg};
 use std::ascii::AsciiExt;
 use std::borrow::ToOwned;
@@ -96,8 +97,9 @@ impl HTMLLinkElement {
     }
 
     pub fn set_stylesheet(&self, s: Arc<Stylesheet>) {
-        assert!(self.stylesheet.borrow().is_none()); // Useful for catching timing issues.
-        *self.stylesheet.borrow_mut() = Some(s);
+        *self.stylesheet.borrow_mut() = Some(s.clone());
+        window_from_node(self).layout_chan().send(Msg::AddStylesheet(s)).unwrap();
+        document_from_node(self).invalidate_stylesheets();
     }
 
     pub fn get_stylesheet(&self) -> Option<Arc<Stylesheet>> {
diff --git a/components/script/stylesheet_loader.rs b/components/script/stylesheet_loader.rs
index cdafde510c9..37b41f53d70 100644
--- a/components/script/stylesheet_loader.rs
+++ b/components/script/stylesheet_loader.rs
@@ -22,7 +22,6 @@ use ipc_channel::router::ROUTER;
 use net_traits::{FetchResponseListener, FetchMetadata, FilteredMetadata, Metadata, NetworkError, ReferrerPolicy};
 use net_traits::request::{CorsSettings, CredentialsMode, Destination, RequestInit, RequestMode, Type as RequestType};
 use network_listener::{NetworkListener, PreInvoke};
-use script_layout_interface::message::Msg;
 use servo_url::ServoUrl;
 use std::mem;
 use std::sync::{Arc, Mutex};
@@ -151,9 +150,7 @@ impl FetchResponseListener for StylesheetContext {
                             sheet.set_disabled(true);
                         }
 
-                        link.set_stylesheet(sheet.clone());
-
-                        win.layout_chan().send(Msg::AddStylesheet(sheet)).unwrap();
+                        link.set_stylesheet(sheet);
                     }
                 }
                 StylesheetContextSource::Import(ref stylesheet) => {
diff --git a/tests/wpt/metadata/MANIFEST.json b/tests/wpt/metadata/MANIFEST.json
index bdf9832d314..36e78ab453c 100644
--- a/tests/wpt/metadata/MANIFEST.json
+++ b/tests/wpt/metadata/MANIFEST.json
@@ -8229,6 +8229,18 @@
      {}
     ]
    ],
+   "html/semantics/document-metadata/the-link-element/stylesheet-change-href.html": [
+    [
+     "/html/semantics/document-metadata/the-link-element/stylesheet-change-href.html",
+     [
+      [
+       "/html/semantics/document-metadata/the-link-element/stylesheet-change-href-ref.html",
+       "=="
+      ]
+     ],
+     {}
+    ]
+   ],
    "html/semantics/document-metadata/the-link-element/stylesheet-empty-href.html": [
     [
      "/html/semantics/document-metadata/the-link-element/stylesheet-empty-href.html",
@@ -51859,11 +51871,21 @@
      {}
     ]
    ],
+   "html/semantics/document-metadata/the-link-element/resources/bad.css": [
+    [
+     {}
+    ]
+   ],
    "html/semantics/document-metadata/the-link-element/resources/empty-href.css": [
     [
      {}
     ]
    ],
+   "html/semantics/document-metadata/the-link-element/resources/good.css": [
+    [
+     {}
+    ]
+   ],
    "html/semantics/document-metadata/the-link-element/resources/stylesheet.css": [
     [
      {}
@@ -51874,6 +51896,11 @@
      {}
     ]
    ],
+   "html/semantics/document-metadata/the-link-element/stylesheet-change-href-ref.html": [
+    [
+     {}
+    ]
+   ],
    "html/semantics/document-metadata/the-link-element/stylesheet-empty-href-ref.html": [
     [
      {}
@@ -174506,10 +174533,18 @@
    "285208d6cf3113ec16bedd107c0740b8c7c8a9d8",
    "testharness"
   ],
+  "html/semantics/document-metadata/the-link-element/resources/bad.css": [
+   "b968e6422a283acc772561f8950171b3a5e00397",
+   "support"
+  ],
   "html/semantics/document-metadata/the-link-element/resources/empty-href.css": [
    "1dcc57d4f3363562322937979cb7828b0c298daa",
    "support"
   ],
+  "html/semantics/document-metadata/the-link-element/resources/good.css": [
+   "04a3a89fe805fc930dc3adfa3a4134b950779697",
+   "support"
+  ],
   "html/semantics/document-metadata/the-link-element/resources/stylesheet.css": [
    "2829167c82bafef6cfea06071007a231aa4277f6",
    "support"
@@ -174518,6 +174553,14 @@
    "e4a66764ea94d51b42d485d75a3305ea2ab79226",
    "support"
   ],
+  "html/semantics/document-metadata/the-link-element/stylesheet-change-href-ref.html": [
+   "cca943d35bd18e99249d50c6d40cc6fe2e328354",
+   "support"
+  ],
+  "html/semantics/document-metadata/the-link-element/stylesheet-change-href.html": [
+   "6083446e9ef1b70f044a353ef96b459956afb1ef",
+   "reftest"
+  ],
   "html/semantics/document-metadata/the-link-element/stylesheet-empty-href-ref.html": [
    "1ac8e070630e58df8489b779bdd75cb2b38c25ef",
    "support"
diff --git a/tests/wpt/web-platform-tests/html/semantics/document-metadata/the-link-element/resources/bad.css b/tests/wpt/web-platform-tests/html/semantics/document-metadata/the-link-element/resources/bad.css
new file mode 100644
index 00000000000..4e1fe36165c
--- /dev/null
+++ b/tests/wpt/web-platform-tests/html/semantics/document-metadata/the-link-element/resources/bad.css
@@ -0,0 +1,4 @@
+p {
+    background-color: red;
+    color: black;
+}
\ No newline at end of file
diff --git a/tests/wpt/web-platform-tests/html/semantics/document-metadata/the-link-element/resources/good.css b/tests/wpt/web-platform-tests/html/semantics/document-metadata/the-link-element/resources/good.css
new file mode 100644
index 00000000000..1da5e2b8cfb
--- /dev/null
+++ b/tests/wpt/web-platform-tests/html/semantics/document-metadata/the-link-element/resources/good.css
@@ -0,0 +1,3 @@
+p {
+    color: green;
+}
\ No newline at end of file
diff --git a/tests/wpt/web-platform-tests/html/semantics/document-metadata/the-link-element/stylesheet-change-href-ref.html b/tests/wpt/web-platform-tests/html/semantics/document-metadata/the-link-element/stylesheet-change-href-ref.html
new file mode 100644
index 00000000000..9ae6e36655d
--- /dev/null
+++ b/tests/wpt/web-platform-tests/html/semantics/document-metadata/the-link-element/stylesheet-change-href-ref.html
@@ -0,0 +1,8 @@
+<!doctype html>
+<meta charset="utf-8">
+<style>
+  p {
+    color: green;
+  }
+</style>
+<p>This text should be green on a white background
diff --git a/tests/wpt/web-platform-tests/html/semantics/document-metadata/the-link-element/stylesheet-change-href.html b/tests/wpt/web-platform-tests/html/semantics/document-metadata/the-link-element/stylesheet-change-href.html
new file mode 100644
index 00000000000..6a3f18de986
--- /dev/null
+++ b/tests/wpt/web-platform-tests/html/semantics/document-metadata/the-link-element/stylesheet-change-href.html
@@ -0,0 +1,13 @@
+<!doctype html>
+<meta charset="utf-8">
+<title>Obtaining a new stylesheet removes styles from the previous stylesheet.</title>
+<link rel=match href=stylesheet-change-href-ref.html>
+<script>
+  function changeHref() {
+    var elem = document.getElementById('stylesheet');
+    elem.href = 'resources/good.css';
+    elem.onload = null;
+  }
+</script>
+<link id=stylesheet rel=stylesheet href="resources/bad.css" onload="changeHref()">
+<p>This text should be green on a white background