Implement closed shadow adjustment for Element.offsetParent

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 c0853351774bffbdfa5051e2dc6152fc5c16f15d..21c673a2d3a94a7a64d1ded1111eac6985884209 100644
--- a/third_party/WebKit/Source/core/dom/Node.cpp
+++ b/third_party/WebKit/Source/core/dom/Node.cpp
@@ -636,6 +636,22 @@ Node& Node::shadowIncludingRoot() const
     return *root;
 }
 
+bool Node::isUnclosedNodeOf(const Node& other) const
+{
+    if (treeScope() == other.treeScope())
+        return true;
+
+    for (TreeScope* scope = &other.treeScope(); scope; scope = scope->parentTreeScope()) {
+        if (scope == treeScope())
+            return true;
+    }
+
+    ContainerNode& root = treeScope().rootNode();
+    if (root.isShadowRoot() && toShadowRoot(root).isOpenOrV0())
+        return other.isUnclosedNodeOf(toShadowRoot(root).host());

[hayato, 2016/06/09 08:22:03]

Is this opposite of the definition? Could you re-check the definition of
"unclosed node"?

We do not have to implement "unclosed node" literally, which is O(N^2).

I think we can implement this in O(N). An algorithm can be:

bool Node::isUnclosedNodeOf(const Node& other) const
{
    if (!isInShadowTree() || treeScope() == other.treeScope())
        return true;
    TreeScope* thisScope = &treeScope();
    while (!thisScope.*isClosed()* && thisScope.parentTreeScope()) {
       thisScope = thisScope->parentScope();
    }
    for (TreeScope* scope = &other.treeScope(); scope; scope =
scope->parentTreeScope()) {
        if (scope == thisScope)
            return true;
    }
    return false;
}

[kochi, 2016/06/09 10:49:39]

Oops, you're right.
I read the latter half of the definition in the opposite way.
This means the test case isn't enough, so I'll add another one to catch it.
Thanks, after checking the tests are working, adopt this alogirthm.

+    return false;
+}
+
 bool Node::needsDistributionRecalc() const
 {
     return shadowIncludingRoot().childNeedsDistributionRecalc();