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 d5ea539ee3527b4a3f90bb8e3b32abb76b499bdf..f6ce013105253907f7f4c35ed0cbb0bf29ca6068 100644
--- a/third_party/WebKit/Source/core/dom/Element.cpp
+++ b/third_party/WebKit/Source/core/dom/Element.cpp
@@ -1570,7 +1570,8 @@ 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) {
@@ -1708,9 +1709,15 @@ void Element::attachLayoutTree(const AttachContext& context) {
     data->clearComputedStyle();
   }
 
-  if (!isActiveSlotOrActiveInsertionPoint())
-    LayoutTreeBuilderForElement(*this, context.resolvedStyle)
-        .createLayoutObjectIfNeeded();
+  if (!isActiveSlotOrActiveInsertionPoint()) {
+    LayoutTreeBuilderForElement builder(*this, context.resolvedStyle);
+    builder.createLayoutObjectIfNeeded();
+
+    if (ComputedStyle* style = builder.resolvedStyle()) {
+      if (!layoutObject() && shouldStoreNonLayoutObjectComputedStyle(*style))
+        storeNonLayoutObjectComputedStyle(style);
+    }
+  }
 
   addCallbackSelectors();
 
@@ -1886,7 +1893,7 @@ void Element::recalcStyle(StyleRecalcChange change, Text* nextTextSibling) {
   if (change >= IndependentInherit || needsStyleRecalc()) {
     if (hasRareData()) {
       ElementRareData* data = elementRareData();
-      if (change != IndependentInherit)
+      if (change != IndependentInherit && !nonLayoutObjectComputedStyle())
         data->clearComputedStyle();
 
       if (change >= IndependentInherit) {
@@ -2009,6 +2016,9 @@ StyleRecalcChange Element::recalcOwnStyle(StyleRecalcChange change,
       // https://codereview.chromium.org/30453002/
       layoutObject->setStyleInternal(newStyle.get());
     }
+  } else if (localChange != NoChange &&
+             shouldStoreNonLayoutObjectComputedStyle(*newStyle)) {
+    storeNonLayoutObjectComputedStyle(newStyle);
   }
 
   if (getStyleChangeType() >= SubtreeStyleChange)
@@ -3160,15 +3170,49 @@ const ComputedStyle* Element::ensureComputedStyle(
           elementStyle->getCachedPseudoStyle(pseudoElementSpecifier))
     return pseudoElementStyle;
 
+  // TODO(ecobos): Passing two times elementStyle may be wrong, though we don't
+  // support display: contents elements' pseudo-elements yet, so this is not a
+  // problem for now.
   RefPtr<ComputedStyle> result =
       document().ensureStyleResolver().pseudoStyleForElement(
           this, PseudoStyleRequest(pseudoElementSpecifier,
                                    PseudoStyleRequest::ForComputedStyle),
-          elementStyle);
+          elementStyle, elementStyle);
   DCHECK(result);
   return elementStyle->addCachedPseudoStyle(result.release());
 }
 
+const ComputedStyle* Element::nonLayoutObjectComputedStyle() const {
+  if (layoutObject() || !hasRareData())
+    return nullptr;
+
+  return elementRareData()->computedStyle();
+}
+
+bool Element::hasDisplayContentsStyle() const {
+  if (const ComputedStyle* style = nonLayoutObjectComputedStyle())
+    return style->display() == EDisplay::Contents;
+  return false;
+}
+
+bool Element::shouldStoreNonLayoutObjectComputedStyle(
+    const ComputedStyle& style) const {
+#if DCHECK_IS_ON()
+  if (style.display() == EDisplay::Contents)
+    DCHECK(!layoutObject());
+#endif
+
+  return style.display() == EDisplay::Contents ||
+         isHTMLOptGroupElement(*this) || isHTMLOptionElement(*this);
+}
+
+void Element::storeNonLayoutObjectComputedStyle(
+    PassRefPtr<ComputedStyle> style) {
+  DCHECK(style);
+  DCHECK(shouldStoreNonLayoutObjectComputedStyle(*style));
+  ensureElementRareData().setComputedStyle(std::move(style));
+}
+
 AtomicString Element::computeInheritedLanguage() const {
   const Node* n = this;
   AtomicString value;
@@ -3909,6 +3953,7 @@ void Element::inlineStyleChanged() {
                                             StyleChangeReason::Inline));
   DCHECK(elementData());
   elementData()->m_styleAttributeIsDirty = true;
+

[rune, 2017/01/27 13:09:23]

Stray newline?

   InspectorInstrumentation::didInvalidateStyleAttr(this);
 
   if (MutationObserverInterestGroup* recipients =