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 3eb14f3b84ec9a5597b32aa9d8f10938000468cf..edf71703e71a08783b74aae7e0db41ecf247c983 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() &&

[esprehn, 2017/02/07 23:50:59]

I think this probably wants to walk the composed tree using
FlatTreeTraversal::parentElement? Otherwise you can end up with non-inert stuff
inside inert stuff using <slot>.

[aboxhall, 2017/02/08 05:26:01]

Done.

+          toElement(node)->hasAttribute(HTMLNames::inertAttr))
+        return true;
+      node = node->parentOrShadowHostElement();
+    } while (node);
+  }
+
   return document().localOwner() && document().localOwner()->isInert();
 }