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 7a5eca1ad8e04ddf27f1747d56fa9275aeb5f0f8..c62031197711027a5f38624d53690c695fb812b5 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 = FlatTreeTraversal::parentElement(*node);
+    } while (node);
+  }
+
   return document().localOwner() && document().localOwner()->isInert();
 }