Bug 1480130 - Shadow DOM interferes with Cmd+click handling, r=felipe

browser/base/content/browser.js

@@ -5891,9 +5891,9 @@ function hrefAndLinkNodeForClickEvent(event) {
             aNode instanceof HTMLLinkElement);
   }
 
-  let node = event.target;
+  let node = event.composedTarget;
   while (node && !isHTMLLink(node)) {
-    node = node.parentNode;
+    node = node.flattenedTreeParentNode;
   }
 
   if (node)
@@ -5901,7 +5901,7 @@ function hrefAndLinkNodeForClickEvent(event) {
 
   // If there is no linkNode, try simple XLink.
   let href, baseURI;
-  node = event.target;
+  node = event.composedTarget;
   while (node && !href) {
     if (node.nodeType == Node.ELEMENT_NODE &&
         (node.localName == "a" ||
@@ -5914,7 +5914,7 @@ function hrefAndLinkNodeForClickEvent(event) {
         break;
       }
     }
-    node = node.parentNode;
+    node = node.flattenedTreeParentNode;
   }
 
   // In case of XLink, we don't return the node we got href from since

browser/base/content/test/general/browser_contentAltClick.js

@@ -17,12 +17,14 @@ ChromeUtils.defineModuleGetter(this, "Downloads",
 
 function setup() {
   Services.prefs.setBoolPref("browser.altClickSave", true);
+  Services.prefs.setBoolPref("dom.webcomponents.shadowdom.enabled", true);
 
   let testPage =
     "data:text/html," +
     '<p><a id="commonlink" href="http://mochi.test/moz/">Common link</a></p>' +
     '<p><math id="mathxlink" xmlns="http://www.w3.org/1998/Math/MathML" xlink:type="simple" xlink:href="http://mochi.test/moz/"><mtext>MathML XLink</mtext></math></p>' +
-    '<p><svg id="svgxlink" xmlns="http://www.w3.org/2000/svg" width="100px" height="50px" version="1.1"><a xlink:type="simple" xlink:href="http://mochi.test/moz/"><text transform="translate(10, 25)">SVG XLink</text></a></svg></p>';
+    '<p><svg id="svgxlink" xmlns="http://www.w3.org/2000/svg" width="100px" height="50px" version="1.1"><a xlink:type="simple" xlink:href="http://mochi.test/moz/"><text transform="translate(10, 25)">SVG XLink</text></a></svg></p><br>' +
+    '<span id="host"></span><script>document.getElementById("host").attachShadow({mode: "closed"}).appendChild(document.getElementById("commonlink").cloneNode(true));</script>';
 
   return BrowserTestUtils.openNewForegroundTab(gBrowser, testPage);
 }
@@ -39,6 +41,7 @@ async function clean_up() {
   await PlacesUtils.history.clear();
 
   Services.prefs.clearUserPref("browser.altClickSave");
+  Services.prefs.clearUserPref("dom.webcomponents.shadowdom.enabled");
   BrowserTestUtils.removeTab(gBrowser.selectedTab);
 }
 
@@ -70,6 +73,34 @@ add_task(async function test_alt_click() {
   await clean_up();
 });
 
+add_task(async function test_alt_click_shadow_dom() {
+  await setup();
+
+  let downloadList = await Downloads.getList(Downloads.ALL);
+  let downloads = [];
+  let downloadView;
+  // When 1 download has been attempted then resolve the promise.
+  let finishedAllDownloads = new Promise( (resolve) => {
+    downloadView = {
+      onDownloadAdded(aDownload) {
+        downloads.push(aDownload);
+        resolve();
+      },
+    };
+  });
+  await downloadList.addView(downloadView);
+  await BrowserTestUtils.synthesizeMouseAtCenter("#host", {altKey: true}, gBrowser.selectedBrowser);
+
+  // Wait for all downloads to be added to the download list.
+  await finishedAllDownloads;
+  await downloadList.removeView(downloadView);
+
+  is(downloads.length, 1, "1 downloads");
+  is(downloads[0].source.url, "http://mochi.test/moz/", "Downloaded #commonlink element in shadow DOM.");
+
+  await clean_up();
+});
+
 add_task(async function test_alt_click_on_xlinks() {
   await setup();
 

browser/modules/ClickEventHandler.jsm

@@ -131,9 +131,9 @@ class ClickEventHandler {
               aNode instanceof content.HTMLLinkElement);
     }
 
-    let node = event.target;
+    let node = event.composedTarget;
     while (node && !isHTMLLink(node)) {
-      node = node.parentNode;
+      node = node.flattenedTreeParentNode;
     }
 
     if (node)
@@ -141,7 +141,7 @@ class ClickEventHandler {
 
     // If there is no linkNode, try simple XLink.
     let href, baseURI;
-    node = event.target;
+    node = event.composedTarget;
     while (node && !href) {
       if (node.nodeType == content.Node.ELEMENT_NODE &&
           (node.localName == "a" ||
@@ -153,7 +153,7 @@ class ClickEventHandler {
           break;
         }
       }
-      node = node.parentNode;
+      node = node.flattenedTreeParentNode;
     }
 
     // In case of XLink, we don't return the node we got href from since