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

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

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All
  * rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved.
  * (http://www.torchmobile.com/)
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
@@ skipping 31 matching lines @@
 #include "core/layout/LayoutView.h"
 #include "core/svg/SVGElement.h"
 #include "platform/RuntimeEnabledFeatures.h"
 
 namespace blink {
 
 LayoutTreeBuilderForElement::LayoutTreeBuilderForElement(Element& element,
                                                          ComputedStyle* style)
     : LayoutTreeBuilder(element, nullptr), m_style(style) {
   DCHECK(!element.isSlotOrActiveInsertionPoint());
+  // FIXME: Move the first-letter logic inside parentLayoutObject too?

[jfernandez, 2016/10/27 17:08:02]

We use to define this kind of comments with TODO (name) instead of fixme, so we
can know who to ask for clarifications, if necessary.

   if (element.isFirstLetterPseudoElement()) {
     if (LayoutObject* nextLayoutObject =
             FirstLetterPseudoElement::firstLetterTextLayoutObject(element))
       m_layoutObjectParent = nextLayoutObject->parent();
-  } else if (ContainerNode* containerNode =
-                 LayoutTreeBuilderTraversal::parent(element)) {
-    m_layoutObjectParent = containerNode->layoutObject();
+  } else {
+    m_layoutObjectParent =
+        LayoutTreeBuilderTraversal::parentLayoutObject(element);
   }
 }
 
 LayoutObject* LayoutTreeBuilderForElement::nextLayoutObject() const {
   DCHECK(m_layoutObjectParent);
 
   if (m_node->isInTopLayer())
     return LayoutTreeBuilderTraversal::nextInTopLayer(*m_node);
 
   if (m_node->isFirstLetterPseudoElement())
@@ skipping 28 matching lines @@
         (!m_layoutObjectParent->node() ||
          !m_layoutObjectParent->node()->isSVGElement()))
       return false;
     if (!toSVGElement(m_node)->isValid())
       return false;
   }
 
   LayoutObject* parentLayoutObject = this->parentLayoutObject();
   if (!parentLayoutObject)
     return false;
+

[jfernandez, 2016/10/27 17:08:01]

Remove this empty line.

   if (!parentLayoutObject->canHaveChildren())
     return false;
 
-  return m_node->layoutObjectIsNeeded(style());
+  // Make sure we keep track of "display: contents" styles.
+  ComputedStyle& style = this->style();

[jfernandez, 2016/10/27 17:08:01]

I think we need to manage this as reference counted, as I commented before.
Anyway, calling to styleRef() is what you want to get a ComputedStyle& style. I
think a "const" cast would be also helpful.

+  if (!m_node->layoutObjectIsNeeded(style)) {
+    if (style.display() == EDisplay::Contents)
+      m_node->storeDisplayContentsStyle(style);

[jfernandez, 2016/10/27 17:08:01]

We need to take care of references here.

+    return false;
+  }
+
+  return true;
 }
 
 ComputedStyle& LayoutTreeBuilderForElement::style() const {
   if (!m_style)
     m_style = m_node->styleForLayoutObject();
   return *m_style;
 }
 
 DISABLE_CFI_PERF
 void LayoutTreeBuilderForElement::createLayoutObject() {
@@ skipping 28 matching lines @@
     if (!newLayoutObject)
       return;
   }
 
   // Note: Adding newLayoutObject instead of layoutObject(). layoutObject() may
   // be a child of newLayoutObject.
   parentLayoutObject->addChild(newLayoutObject, nextLayoutObject);
 }
 
 void LayoutTreeBuilderForText::createLayoutObject() {
-  ComputedStyle& style = m_layoutObjectParent->mutableStyleRef();
+  ComputedStyle& style = *m_style;

[jfernandez, 2016/10/27 17:08:01]

The removed code was like that becase we wanted a mutable instance. I think we
need a similar workflow to clarify we are going to modify an instance that it
should be const otherwise.

+
+  DCHECK(m_style == m_layoutObjectParent->style() ||
+         toElement(LayoutTreeBuilderTraversal::parent(*m_node))
+             ->displayContentsStyle());
 
   DCHECK(m_node->textLayoutObjectIsNeeded(style, *m_layoutObjectParent));
 
   LayoutText* newLayoutObject = m_node->createTextLayoutObject(style);
   if (!m_layoutObjectParent->isChildAllowed(newLayoutObject, style)) {
     newLayoutObject->destroy();
     return;
   }
 
   // Make sure the LayoutObject already knows it is going to be added to a
   // LayoutFlowThread before we set the style for the first time. Otherwise code
   // using inLayoutFlowThread() in the styleWillChange and styleDidChange will
   // fail.
   newLayoutObject->setIsInsideFlowThread(
       m_layoutObjectParent->isInsideFlowThread());
 
   LayoutObject* nextLayoutObject = this->nextLayoutObject();
   m_node->setLayoutObject(newLayoutObject);
   // Parent takes care of the animations, no need to call setAnimatableStyle.
   newLayoutObject->setStyle(&style);
   m_layoutObjectParent->addChild(newLayoutObject, nextLayoutObject);
 }
 
 }  // namespace blink