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

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

Index: third_party/WebKit/Source/core/dom/Element.cpp
diff --git a/third_party/WebKit/Source/core/dom/Element.cpp b/third_party/WebKit/Source/core/dom/Element.cpp
index 24b75742fc9986422bbe76bbeb7380fefc21829f..e4589602368c0ff0cd546ec20d1ce10059b2fa1d 100644
--- a/third_party/WebKit/Source/core/dom/Element.cpp
+++ b/third_party/WebKit/Source/core/dom/Element.cpp
@@ -1527,7 +1527,8 @@ const AtomicString Element::imageSourceURL() const {
 }
 
 bool Element::layoutObjectIsNeeded(const ComputedStyle& style) {
-  return style.display() != EDisplay::None;
+  return style.display() != EDisplay::None &&
+         style.display() != EDisplay::Contents;
 }
 
 LayoutObject* Element::createLayoutObject(const ComputedStyle& style) {
@@ -3133,6 +3134,22 @@ const ComputedStyle* Element::ensureComputedStyle(
   return elementStyle->addCachedPseudoStyle(result.release());
 }
 
+ComputedStyle* Element::displayContentsStyle() const {
+  if (layoutObject() || !hasRareData())
+    return 0;

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

return nullptr

+
+  ComputedStyle* style = elementRareData()->computedStyle();
+  if (!style || style->display() != EDisplay::Contents)
+    return 0;

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

return nullptr

+
+  return style;
+}
+
+void Element::storeDisplayContentsStyle(ComputedStyle& style) {
+  DCHECK_EQ(style.display(), EDisplay::Contents);
+  ensureElementRareData().setComputedStyle(&style);

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

The setComputedStyle argument is a PassRefPtr so I think we would need to ensure
we manage references appropriately. I think we can use std::move to transfer the
reference ownership.  

I think we can also define storeDisplayContentsStyle as Ref<ComputedStyle> as
well.

+}
+
 AtomicString Element::computeInheritedLanguage() const {
   const Node* n = this;
   AtomicString value;