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 cbc5281a0e8e4324bd92f5e5cdd5b1e76f40b19c..b768c2955dc261efd120a484dea6c8f532dfe58b 100644
--- a/third_party/WebKit/Source/core/dom/Node.cpp
+++ b/third_party/WebKit/Source/core/dom/Node.cpp
@@ -771,6 +771,16 @@ bool Node::isInert() const
     const HTMLDialogElement* dialog = document().activeModalDialog();
     if (dialog && this != document() && (!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();
 }