Look for favicon URLs (and similar <link>s) in SVG documents

third_party/WebKit/LayoutTests/svg/custom/favicon-link.svg

Index: third_party/WebKit/LayoutTests/svg/custom/favicon-link.svg
diff --git a/third_party/WebKit/LayoutTests/svg/custom/favicon-link.svg b/third_party/WebKit/LayoutTests/svg/custom/favicon-link.svg
new file mode 100644
index 0000000000000000000000000000000000000000..bd7172b75935b7f13dc03e7198f78ff6300fe7ff
--- /dev/null
+++ b/third_party/WebKit/LayoutTests/svg/custom/favicon-link.svg
@@ -0,0 +1,30 @@
+<svg xmlns="http://www.w3.org/2000/svg"
+     xmlns:html="http://www.w3.org/1999/xhtml">
+  <defs>
+    <html:link rel="shortcut icon" href="icon1.png"/>
+    <html:link rel="shortcut icon" href="icon2.png"/>
+    <html:link rel="shortcut icon" href="icon3.png"/>
+  </defs>
+  <text y="20"></text>
+  <defs>
+    <html:link rel="shortcut icon" href="icon4.png"/>
+    <html:link rel="shortcut icon" href="icon5.png"/>
+  </defs>
+  <html:link rel="shortcut icon" href="icon6.png"/>
+  <script>
+    <![CDATA[
+      if (window.testRunner)
+        testRunner.dumpAsText();
+      let icons = internals.shortcutIconURLs(document);
+      let passed = icons.length === 6 &&
+                   icons[0].endsWith('icon6.png') &&
+                   icons[1].endsWith('icon5.png') &&
+                   icons[2].endsWith('icon4.png') &&
+                   icons[3].endsWith('icon3.png') &&
+                   icons[4].endsWith('icon2.png') &&
+                   icons[5].endsWith('icon1.png');
+      let resultNode = document.querySelector('text');
+      resultNode.textContent = passed ? "PASS" : "FAIL";
+    ]]>
+  </script>
+</svg>