Do not use a non-standard label attribute in shadow-dom.js

third_party/WebKit/LayoutTests/shadow-dom/resources/shadow-dom.js

Index: third_party/WebKit/LayoutTests/shadow-dom/resources/shadow-dom.js
diff --git a/third_party/WebKit/LayoutTests/shadow-dom/resources/shadow-dom.js b/third_party/WebKit/LayoutTests/shadow-dom/resources/shadow-dom.js
index 7b4841fb571d55c4bb83db470d6140107bb12278..488283fcb35c6f79cab84a9c447d54cc78985d1d 100644
--- a/third_party/WebKit/LayoutTests/shadow-dom/resources/shadow-dom.js
+++ b/third_party/WebKit/LayoutTests/shadow-dom/resources/shadow-dom.js
@@ -67,27 +67,27 @@ function getNodeInComposedTree(path)
 
 function createTestTree(node) {
 
-  let labels = {};
+  let ids = {};
 
   function attachShadowFromTemplate(template) {
     let parent = template.parentNode;
     parent.removeChild(template);
     let shadowRoot = parent.attachShadow({mode: template.getAttribute('data-mode')});
-    let label = template.getAttribute('label');
-    if (label) {
-      shadowRoot.id = label;
-      labels[label] = shadowRoot;
+    let id = template.id;
+    if (id) {
+      shadowRoot.id = id;
+      ids[id] = shadowRoot;
     }
     shadowRoot.appendChild(document.importNode(template.content, true));
     return shadowRoot;
   }
 
   function walk(root) {
-    if (root.getAttribute && root.getAttribute('label')) {
-      labels[root.getAttribute('label')] = root;
+    if (root.id) {
+      ids[root.id] = root;
     }
-    for (let e of Array.from(root.querySelectorAll('[label]'))) {
-      labels[e.getAttribute('label')] = e;
+    for (let e of Array.from(root.querySelectorAll('[id]'))) {
+      ids[e.id] = e;
     }
     for (let e of Array.from(root.querySelectorAll('template'))) {
       walk(attachShadowFromTemplate(e));
@@ -95,15 +95,12 @@ function createTestTree(node) {
   }
 
   walk(node.cloneNode(true));
-  return labels;
+  return ids;
 }
 
 function dispatchEventWithLog(nodes, target, event) {
 
   function labelFor(e) {
-    if (e.getAttribute && e.getAttribute('label')) {
-      return e.getAttribute('label');
-    }
     return e.id || e.tagName;
   }
 
@@ -114,12 +111,12 @@ function dispatchEventWithLog(nodes, target, event) {
     for (let node = startingNode; node; node = node.parentNode) {
       if (attachedNodes.indexOf(node) >= 0)
         continue;
-      let label = labelFor(node);
-      if (!label)
+      let id = node.id;
+      if (!id)
         continue;
       attachedNodes.push(node);
       node.addEventListener(event.type, (e) => {
-        log.push([label,
+        log.push([id,
                   event.relatedTarget ? labelFor(event.relatedTarget) : null,
                   event.composedPath().map((n) => {
                     return labelFor(n);