Implement the inert attribute

third_party/WebKit/LayoutTests/inspector-protocol/accessibility/accessibility-ignoredNodes-expected.txt

Index: third_party/WebKit/LayoutTests/inspector-protocol/accessibility/accessibility-ignoredNodes-expected.txt
diff --git a/third_party/WebKit/LayoutTests/inspector-protocol/accessibility/accessibility-ignoredNodes-expected.txt b/third_party/WebKit/LayoutTests/inspector-protocol/accessibility/accessibility-ignoredNodes-expected.txt
index b932ae5638e783ce7c84c4c699ee51b3a8cb4dd8..693860a4643d5dbff2cd620fb739d46c9da888df 100644
--- a/third_party/WebKit/LayoutTests/inspector-protocol/accessibility/accessibility-ignoredNodes-expected.txt
+++ b/third_party/WebKit/LayoutTests/inspector-protocol/accessibility/accessibility-ignoredNodes-expected.txt
@@ -5,7 +5,8 @@ hidden non-treeitem
 Descendant of aria-hidden node
 List item also presentational
 Div in list isn't presentational
-Content within label refers to label container     
+Content within label refers to label container      inert button
+button in inert subtree
 
 WebArea
   tree
@@ -178,8 +179,16 @@ WebArea
 }
 
 WebArea
+  Div
+  tree
+  img
+  button "Buttons are leaf nodes"
+  text "List item also presentational"
   *Div
     text "Div in list isn't presentational"
+  checkbox "Content within label refers to label container"
+  Div
+  Div
 {
   "nodeId": "<string>",
   "ignored": false,
@@ -414,3 +423,50 @@ WebArea
   "domNode": "select"
 }
 
+WebArea
+  *Ignored
+{
+  "nodeId": "<string>",
+  "ignored": true,
+  "ignoredReasons": [
+    {
+      "name": "inertElement",
+      "value": {
+        "type": "boolean",
+        "value": true
+      }
+    }
+  ],
+  "role": {
+    "type": "internalRole",
+    "value": "Ignored"
+  },
+  "domNode": "button"
+}
+
+WebArea
+  *Ignored
+{
+  "nodeId": "<string>",
+  "ignored": true,
+  "ignoredReasons": [
+    {
+      "name": "inertSubtree",
+      "value": {
+        "type": "idref",
+        "relatedNodes": [
+          {
+            "idref": "inert-root",
+            "nodeResult": "div#inert-root"
+          }
+        ]
+      }
+    }
+  ],
+  "role": {
+    "type": "internalRole",
+    "value": "Ignored"
+  },
+  "domNode": "button"
+}
+