Support display: contents for elements, first-line and first-letter pseudos.

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

Index: third_party/WebKit/Source/core/dom/LayoutTreeBuilderTraversal.cpp
diff --git a/third_party/WebKit/Source/core/dom/LayoutTreeBuilderTraversal.cpp b/third_party/WebKit/Source/core/dom/LayoutTreeBuilderTraversal.cpp
index df6ce336cd67a569ae6ee9b3a8fafd813493c799..3252605f6069636e5415ffbfa9a7b0a7855a4ad5 100644
--- a/third_party/WebKit/Source/core/dom/LayoutTreeBuilderTraversal.cpp
+++ b/third_party/WebKit/Source/core/dom/LayoutTreeBuilderTraversal.cpp
@@ -35,11 +35,19 @@ namespace blink {
 
 namespace LayoutTreeBuilderTraversal {
 
+inline static bool hasDisplayContentsStyle(const Node& node) {
+  return node.isElementNode() && toElement(node).displayContentsStyle();
+}
+
 static bool isLayoutObjectReparented(const LayoutObject* layoutObject) {
   if (!layoutObject->node()->isElementNode())
     return false;
   if (toElement(layoutObject->node())->isInTopLayer())
     return true;
+
+  // NB: We intentionally ignore display:contents children here, since we aim to
+  // find them in the traversal.

[rune, 2016/11/08 13:09:20]

I think you can just remove this comment. The reparenting (the term reparenting
is not defined in a spec afaik) is about reparenting _elements_ into the top
layer to the extent it's defined in the fullscreen spec. Adding a comment about
display:contents here will just be confusing, I think.

[emilio, 2016/11/08 15:43:01]

Oh, ok, I see, will do.

+
   return false;
 }
 
@@ -68,6 +76,16 @@ ContainerNode* parent(const Node& node, ParentDetails* details) {
   return FlatTreeTraversal::parent(node, details);
 }
 
+LayoutObject* parentLayoutObject(const Node& node) {
+  ContainerNode* parent = LayoutTreeBuilderTraversal::parent(node);
+
+  while (parent && hasDisplayContentsStyle(*parent)) {
+    parent = LayoutTreeBuilderTraversal::parent(*parent);
+  }
+
+  return parent ? parent->layoutObject() : nullptr;
+}
+
 Node* nextSibling(const Node& node) {
   if (node.isBeforePseudoElement()) {
     assertPseudoElementParent(toPseudoElement(node));
@@ -214,28 +232,100 @@ Node* next(const Node& node, const Node* stayWithin) {
   return nextSkippingChildren(node, stayWithin);
 }
 
-LayoutObject* nextSiblingLayoutObject(const Node& node, int32_t limit) {
-  DCHECK(limit == kTraverseAllSiblings || limit >= 0) << limit;
-  for (Node* sibling = LayoutTreeBuilderTraversal::nextSibling(node);
-       sibling && limit-- != 0;
+static LayoutObject* nextSiblingLayoutObjectInternal(Node* node,
+                                                     int32_t& limit) {
+  for (Node* sibling = node; sibling && limit-- != 0;
        sibling = LayoutTreeBuilderTraversal::nextSibling(*sibling)) {
     LayoutObject* layoutObject = sibling->layoutObject();
+
+#if DCHECK_IS_ON()
+    if (hasDisplayContentsStyle(*sibling))
+      DCHECK(!layoutObject);
+#endif
+
+    if (!layoutObject && hasDisplayContentsStyle(*sibling)) {
+      layoutObject = nextSiblingLayoutObjectInternal(
+          pseudoAwareFirstChild(*sibling), limit);
+      if (layoutObject)
+        return layoutObject;
+      if (!limit)
+        return nullptr;
+    }
+
     if (layoutObject && !isLayoutObjectReparented(layoutObject))
       return layoutObject;
   }
-  return 0;
+
+  return nullptr;
 }
 
-LayoutObject* previousSiblingLayoutObject(const Node& node, int32_t limit) {
+LayoutObject* nextSiblingLayoutObject(const Node& node, int32_t limit) {
   DCHECK(limit == kTraverseAllSiblings || limit >= 0) << limit;
-  for (Node* sibling = LayoutTreeBuilderTraversal::previousSibling(node);
-       sibling && limit-- != 0;
+  if (LayoutObject* foundLayoutObject = nextSiblingLayoutObjectInternal(
+          LayoutTreeBuilderTraversal::nextSibling(node), limit))
+    return foundLayoutObject;
+
+  Node* maybeDisplayContentsParent = LayoutTreeBuilderTraversal::parent(node);
+  while (limit && maybeDisplayContentsParent &&
+         hasDisplayContentsStyle(*maybeDisplayContentsParent)) {
+    Node* displayContentsSibling =
+        LayoutTreeBuilderTraversal::nextSibling(*maybeDisplayContentsParent);
+    if (LayoutObject* siblingLayoutObject =
+            nextSiblingLayoutObjectInternal(displayContentsSibling, limit))
+      return siblingLayoutObject;
+    maybeDisplayContentsParent =
+        LayoutTreeBuilderTraversal::parent(*maybeDisplayContentsParent);
+  }
+
+  return nullptr;
+}
+
+static LayoutObject* previousSiblingLayoutObjectInternal(Node* node,
+                                                         int32_t& limit) {
+  for (Node* sibling = node; sibling && limit-- != 0;
        sibling = LayoutTreeBuilderTraversal::previousSibling(*sibling)) {
     LayoutObject* layoutObject = sibling->layoutObject();
+
+#if DCHECK_IS_ON()
+    if (hasDisplayContentsStyle(*sibling))
+      DCHECK(!layoutObject);
+#endif
+
+    if (!layoutObject && hasDisplayContentsStyle(*sibling)) {
+      layoutObject = nextSiblingLayoutObjectInternal(
+          pseudoAwareFirstChild(*sibling), limit);
+      if (layoutObject)
+        return layoutObject;
+      if (!limit)
+        return nullptr;
+    }
+
     if (layoutObject && !isLayoutObjectReparented(layoutObject))
       return layoutObject;
   }
-  return 0;
+
+  return nullptr;
+}
+
+LayoutObject* previousSiblingLayoutObject(const Node& node, int32_t limit) {
+  DCHECK(limit == kTraverseAllSiblings || limit >= 0) << limit;
+  if (LayoutObject* foundLayoutObject = previousSiblingLayoutObjectInternal(
+          LayoutTreeBuilderTraversal::previousSibling(node), limit))
+    return foundLayoutObject;
+
+  Node* maybeDisplayContentsParent = LayoutTreeBuilderTraversal::parent(node);
+  while (limit && maybeDisplayContentsParent &&
+         hasDisplayContentsStyle(*maybeDisplayContentsParent)) {
+    Node* displayContentsSibling = LayoutTreeBuilderTraversal::previousSibling(
+        *maybeDisplayContentsParent);
+    if (LayoutObject* siblingLayoutObject =
+            previousSiblingLayoutObjectInternal(displayContentsSibling, limit))
+      return siblingLayoutObject;
+    maybeDisplayContentsParent =
+        LayoutTreeBuilderTraversal::parent(*maybeDisplayContentsParent);
+  }
+
+  return nullptr;
 }
 
 LayoutObject* nextInTopLayer(const Element& element) {