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

third_party/WebKit/Source/core/css/resolver/StyleAdjuster.cpp

Index: third_party/WebKit/Source/core/css/resolver/StyleAdjuster.cpp
diff --git a/third_party/WebKit/Source/core/css/resolver/StyleAdjuster.cpp b/third_party/WebKit/Source/core/css/resolver/StyleAdjuster.cpp
index 127e05c930c7092e5c882155c9ac68d0d255469f..dc21e25edac0fcf4d09c08933395faf70e5057f6 100644
--- a/third_party/WebKit/Source/core/css/resolver/StyleAdjuster.cpp
+++ b/third_party/WebKit/Source/core/css/resolver/StyleAdjuster.cpp
@@ -75,6 +75,7 @@ static EDisplay equivalentBlockDisplay(EDisplay display) {
     case EDisplay::InlineGrid:
       return EDisplay::Grid;
 
+    case EDisplay::Contents:
     case EDisplay::Inline:
     case EDisplay::InlineBlock:
     case EDisplay::TableRowGroup:
@@ -87,7 +88,6 @@ static EDisplay equivalentBlockDisplay(EDisplay display) {
     case EDisplay::TableCaption:
       return EDisplay::Block;
     case EDisplay::None:
-    case EDisplay::Contents:
       ASSERT_NOT_REACHED();
       return display;
   }
@@ -131,9 +131,9 @@ static bool isInTopLayer(const Element* element, const ComputedStyle& style) {
          style.styleType() == PseudoIdBackdrop;
 }
 
-static bool parentStyleForcesZIndexToCreateStackingContext(
-    const ComputedStyle& parentStyle) {
-  return parentStyle.isDisplayFlexibleOrGridBox();
+static bool layoutParentStyleForcesZIndexToCreateStackingContext(
+    const ComputedStyle& layoutParentStyle) {
+  return layoutParentStyle.isDisplayFlexibleOrGridBox();
 }
 
 void StyleAdjuster::adjustStyleForEditing(ComputedStyle& style) {
@@ -324,16 +324,19 @@ static void adjustOverflow(ComputedStyle& style) {
 }
 
 static void adjustStyleForDisplay(ComputedStyle& style,
-                                  const ComputedStyle& parentStyle,
+                                  const ComputedStyle& layoutParentStyle,
                                   Document* document) {
   if (style.display() == EDisplay::Block && !style.isFloating())
     return;
 
+  if (style.display() == EDisplay::Contents)
+    return;
+
   // FIXME: Don't support this mutation for pseudo styles like first-letter or
   // first-line, since it's not completely clear how that should work.
   if (style.display() == EDisplay::Inline &&
       style.styleType() == PseudoIdNone &&
-      style.getWritingMode() != parentStyle.getWritingMode())
+      style.getWritingMode() != layoutParentStyle.getWritingMode())
     style.setDisplay(EDisplay::InlineBlock);
 
   // After performing the display mutation, check table rows. We do not honor
@@ -365,7 +368,7 @@ static void adjustStyleForDisplay(ComputedStyle& style,
       style.display() == EDisplay::TableRow ||
       style.display() == EDisplay::TableRowGroup ||
       style.display() == EDisplay::TableCell)
-    style.setWritingMode(parentStyle.getWritingMode());
+    style.setWritingMode(layoutParentStyle.getWritingMode());
 
   // FIXME: Since we don't support block-flow on flexible boxes yet, disallow
   // setting of block-flow to anything other than TopToBottomWritingMode.
@@ -375,7 +378,7 @@ static void adjustStyleForDisplay(ComputedStyle& style,
        style.display() == EDisplay::WebkitInlineBox))
     style.setWritingMode(WritingMode::kHorizontalTb);
 
-  if (parentStyle.isDisplayFlexibleOrGridBox()) {
+  if (layoutParentStyle.isDisplayFlexibleOrGridBox()) {
     style.setFloating(EFloat::kNone);
     style.setDisplay(equivalentBlockDisplay(style.display()));
 
@@ -393,9 +396,9 @@ static void adjustStyleForDisplay(ComputedStyle& style,
 
 void StyleAdjuster::adjustComputedStyle(ComputedStyle& style,
                                         const ComputedStyle& parentStyle,
+                                        const ComputedStyle& layoutParentStyle,
                                         Element* element) {
-  if (style.display() != EDisplay::None &&
-      style.display() != EDisplay::Contents) {
+  if (style.display() != EDisplay::None) {
     if (element && element->isHTMLElement())
       adjustStyleForHTMLElement(style, toHTMLElement(*element));
 
@@ -408,15 +411,18 @@ void StyleAdjuster::adjustComputedStyle(ComputedStyle& style,
 
     // Absolute/fixed positioned elements, floating elements and the document
     // element need block-like outside display.
-    if (style.hasOutOfFlowPosition() || style.isFloating() ||
-        (element && element->document().documentElement() == element))
+    if (style.display() != EDisplay::Contents &&
+        (style.hasOutOfFlowPosition() || style.isFloating()))
+      style.setDisplay(equivalentBlockDisplay(style.display()));
+
+    if (element && element->document().documentElement() == element)
       style.setDisplay(equivalentBlockDisplay(style.display()));
 
     // We don't adjust the first letter style earlier because we may change the
     // display setting in adjustStyeForTagName() above.
     adjustStyleForFirstLetter(style);
 
-    adjustStyleForDisplay(style, parentStyle,
+    adjustStyleForDisplay(style, layoutParentStyle,
                           element ? &element->document() : 0);
 
     // Paint containment forces a block formatting context, so we must coerce
@@ -432,7 +438,8 @@ void StyleAdjuster::adjustComputedStyle(ComputedStyle& style,
 
   // Make sure our z-index value is only applied if the object is positioned.
   if (style.position() == EPosition::kStatic &&
-      !parentStyleForcesZIndexToCreateStackingContext(parentStyle)) {
+      !layoutParentStyleForcesZIndexToCreateStackingContext(
+          layoutParentStyle)) {
     style.setIsStackingContext(false);
     // TODO(alancutter): Avoid altering z-index here.
     if (!style.hasAutoZIndex())