Implement the inert attribute

third_party/WebKit/Source/core/dom/Node.cpp

Index: third_party/WebKit/Source/core/dom/Node.cpp
diff --git a/third_party/WebKit/Source/core/dom/Node.cpp b/third_party/WebKit/Source/core/dom/Node.cpp
index 600af2f195aadbeb1136ad3b602b9d93b4d01122..8ab5a175be03c4b89defc9e5a44b310ff1f5cec2 100644
--- a/third_party/WebKit/Source/core/dom/Node.cpp
+++ b/third_party/WebKit/Source/core/dom/Node.cpp
@@ -779,6 +779,17 @@ bool Node::isInert() const {
       (!canParticipateInFlatTree() ||
        !FlatTreeTraversal::containsIncludingPseudoElement(*dialog, *this)))
     return true;
+
+  if (RuntimeEnabledFeatures::inertAttributeEnabled()) {
+    const Node* node = this;
+    do {
+      if (node->isElementNode() &&
+          toElement(node)->hasAttribute(HTMLNames::inertAttr))
+        return true;
+      node = node->parentOrShadowHostElement();
+    } while (node);
+  }
+
   return document().localOwner() && document().localOwner()->isInert();
 }