Bug 1730625 - Walk the flat tree to search for links. r=smaug

Also make some other context-menu code a lot more straight-forward, and
remove some enabledness checks now that shadow dom can't be disabled.

Differential Revision: https://phabricator.services.mozilla.com/D125487

browser/actors/ContextMenuChild.jsm

@@ -778,21 +778,14 @@ class ContextMenuChild extends JSWindowActorChild {
 
     // Set the node to containing <video>/<audio>/<embed>/<object> if the node
     // is in the videocontrols UA Widget.
-    if (this.contentWindow.ShadowRoot) {
-      let n = node;
-      while (n) {
-        if (n instanceof this.contentWindow.ShadowRoot) {
+    if (node.containingShadowRoot?.isUAWidget()) {
+      const host = node.containingShadowRoot.host;
       if (
-            n.host instanceof this.contentWindow.HTMLMediaElement ||
-            n.host instanceof this.contentWindow.HTMLEmbedElement ||
-            n.host instanceof this.contentWindow.HTMLObjectElement
+        host instanceof this.contentWindow.HTMLMediaElement ||
+        host instanceof this.contentWindow.HTMLEmbedElement ||
+        host instanceof this.contentWindow.HTMLObjectElement
       ) {
-            node = n.host;
-            break;
-          }
-          break;
-        }
-        n = n.parentNode;
+        node = host;
       }
     }
 
@@ -1165,7 +1158,7 @@ class ContextMenuChild extends JSWindowActorChild {
         }
       }
 
-      elem = elem.parentNode;
+      elem = elem.flattenedTreeParentNode;
     }
 
     // See if the user clicked in a frame.

browser/base/content/test/contextMenu/browser_contextmenu.js

@@ -174,8 +174,7 @@ add_task(async function test_plaintext() {
   ]);
 });
 
-add_task(async function test_link() {
-  await test_contextmenu("#test-link", [
+const kLinkItems = [
   "context-openlinkintab",
   true,
   ...(hasContainers ? ["context-openlinkinusercontext-menu", true] : []),
@@ -201,44 +200,24 @@ add_task(async function test_link() {
   true,
   "context-searchselect-private",
   true,
-  ]);
+];
+
+add_task(async function test_link() {
+  await test_contextmenu("#test-link", kLinkItems);
 });
 
 add_task(async function test_link_in_shadow_dom() {
-  await test_contextmenu(
-    "#shadow-host",
-    [
-      "context-openlinkintab",
-      true,
-      ...(hasContainers ? ["context-openlinkinusercontext-menu", true] : []),
-      // We need a blank entry here because the containers submenu is
-      // dynamically generated with no ids.
-      ...(hasContainers ? ["", null] : []),
-      "context-openlink",
-      true,
-      "context-openlinkprivate",
-      true,
-      "---",
-      null,
-      "context-bookmarklink",
-      true,
-      "context-savelink",
-      true,
-      ...(hasPocket ? ["context-savelinktopocket", true] : []),
-      "context-copylink",
-      true,
-      "---",
-      null,
-      "context-searchselect",
-      true,
-      "context-searchselect-private",
-      true,
-    ],
-    {
+  await test_contextmenu("#shadow-host", kLinkItems, {
     offsetX: 6,
     offsetY: 6,
-    }
-  );
+  });
+});
+
+add_task(async function test_link_over_shadow_dom() {
+  await test_contextmenu("#shadow-host-in-link", kLinkItems, {
+    offsetX: 6,
+    offsetY: 6,
+  });
 });
 
 add_task(async function test_mailto() {

browser/base/content/test/contextMenu/subtst_contextmenu.html

@@ -9,12 +9,14 @@ Browser context menu subtest.
 <div id="test-text">Lorem ipsum dolor sit amet, consectetuer adipiscing elit.</div>
 <a id="test-link" href="http://mozilla.com">Click the monkey!</a>
 <div id="shadow-host"></div>
+<a href="http://mozilla.com" style="display: block">
+  <span id="shadow-host-in-link"></span>
+</a>
 <script>
-// Create the shadow DOM in case shadow DOM is enabled.
-if ("ShadowRoot" in this) {
-  var sr = document.getElementById("shadow-host").attachShadow({mode: "closed"});
-  sr.innerHTML = "<a href='http://mozilla.com'>Click the monkey!</a>";
-}
+document.getElementById("shadow-host").attachShadow({ mode: "closed" }).innerHTML =
+  "<a href='http://mozilla.com'>Click the monkey!</a>";
+document.getElementById("shadow-host-in-link").attachShadow({ mode: "closed" }).innerHTML =
+  "<span>Click the monkey!</span>";
 </script>
 <a id="test-mailto" href="mailto:codemonkey@mozilla.com">Mail the monkey!</a><br>
 <input id="test-input"><br>