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

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

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Peter Kelly (pmk@post.com)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012, 2013 Apple Inc.
  * All rights reserved.
  *           (C) 2007 Eric Seidel (eric@webkit.org)
  *
@@ skipping 1556 matching lines @@
     return parent->locateNamespacePrefix(namespaceToLocate);
 
   return nullAtom;
 }
 
 const AtomicString Element::imageSourceURL() const {
   return getAttribute(srcAttr);
 }
 
 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) {
   return LayoutObject::createObject(this, style);
 }
 
 Node::InsertionNotificationRequest Element::insertedInto(
     ContainerNode* insertionPoint) {
   // need to do superclass processing first so isConnected() is true
   // by the time we reach updateId
@@ skipping 120 matching lines @@
 void Element::attachLayoutTree(const AttachContext& context) {
   DCHECK(document().inStyleRecalc());
 
   // We've already been through detach when doing an attach, but we might
   // need to clear any state that's been added since then.
   if (hasRareData() && needsAttach()) {
     ElementRareData* data = elementRareData();
     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();
 
   if (hasRareData() && !layoutObject()) {
     if (ElementAnimations* elementAnimations =
             elementRareData()->elementAnimations()) {
       elementAnimations->cssAnimations().cancel();
       elementAnimations->setAnimationStyleChange(false);
     }
   }
@@ skipping 155 matching lines @@
   DCHECK(!document().lifecycle().inDetach());
   DCHECK(!parentOrShadowHostNode()->needsStyleRecalc());
   DCHECK(inActiveDocument());
 
   if (hasCustomStyleCallbacks())
     willRecalcStyle(change);
 
   if (change >= IndependentInherit || needsStyleRecalc()) {
     if (hasRareData()) {
       ElementRareData* data = elementRareData();
-      if (change != IndependentInherit)
-        data->clearComputedStyle();
+      if (change != IndependentInherit) {
+        // We keep the old computed style around for display: contents, option
+        // and optgroup. This way we can call stylePropagationDiff accurately.
+        //
+        // We could clear it always, but we'd have more expensive restyles for
+        // children.
+        //
+        // Note that we can't just keep stored other kind of non-layout object
+        // computed style (like the one that gets set when getComputedStyle is
+        // called on a display: none element), because that is a sizable memory
+        // hit.
+        //
+        // Also, we don't want to leave a stale computed style, which may happen
+        // if we don't end up calling recalcOwnStyle because there's no parent
+        // style.
+        const ComputedStyle* nonLayoutStyle = nonLayoutObjectComputedStyle();
+        if (!nonLayoutStyle ||
+            !shouldStoreNonLayoutObjectComputedStyle(*nonLayoutStyle) ||
+            !parentComputedStyle()) {
+          data->clearComputedStyle();
+        }
+      }
 
       if (change >= IndependentInherit) {
         if (ElementAnimations* elementAnimations = data->elementAnimations())
           elementAnimations->setAnimationStyleChange(false);
       }
     }
     if (parentComputedStyle())
       change = recalcOwnStyle(change, nextTextSibling);
     clearNeedsStyleRecalc();
     clearNeedsReattachLayoutTree();
@@ skipping 101 matching lines @@
         pseudoStyleCacheIsInvalid(oldStyle.get(), newStyle.get())) {
       layoutObject->setStyle(newStyle.get());
     } else {
       // Although no change occurred, we use the new style so that the cousin
       // style sharing code won't get fooled into believing this style is the
       // same.
       // FIXME: We may be able to remove this hack, see discussion in
       // https://codereview.chromium.org/30453002/
       layoutObject->setStyleInternal(newStyle.get());
     }
+  } else if (localChange != NoChange &&
+             shouldStoreNonLayoutObjectComputedStyle(*newStyle)) {
+    storeNonLayoutObjectComputedStyle(newStyle);
   }
 
   if (getStyleChangeType() >= SubtreeStyleChange)
     return Force;
 
   if (change > Inherit || localChange > Inherit)
     return max(localChange, change);
 
   if (localChange < IndependentInherit) {
     if (oldStyle->hasChildDependentFlags()) {
@@ skipping 1137 matching lines @@
     elementStyle = rareData.computedStyle();
   }
 
   if (!pseudoElementSpecifier)
     return elementStyle;
 
   if (ComputedStyle* pseudoElementStyle =
           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;
   // The language property is inherited, so we iterate over the parents to find
   // the first language.
   do {
     if (n->isElementNode()) {
       if (const ElementData* elementData = toElement(n)->elementData()) {
         AttributeCollection attributes = elementData->attributes();
         // Spec: xml:lang takes precedence -- http://www.w3.org/TR/xhtml1/#C_7
@@ skipping 944 matching lines @@
 }
 
 DEFINE_TRACE_WRAPPERS(Element) {
   if (hasRareData()) {
     visitor->traceWrappers(elementRareData());
   }
   ContainerNode::traceWrappers(visitor);
 }
 
 }  // namespace blink