add 'slow' prefix to RenderObject's firstChild() / lastChild() methods

Source/core/rendering/RenderBox.cpp

Index: Source/core/rendering/RenderBox.cpp
diff --git a/Source/core/rendering/RenderBox.cpp b/Source/core/rendering/RenderBox.cpp
index 2e451c543c83df43738c0207d08f829fe8f6b6ec..eebdb043f95a38d38b6ff920c4d5ee4d6eb0c017 100644
--- a/Source/core/rendering/RenderBox.cpp
+++ b/Source/core/rendering/RenderBox.cpp
@@ -191,7 +191,7 @@ void RenderBox::styleDidChange(StyleDifference diff, const RenderStyle* oldStyle
             parent()->setChildNeedsLayout();
     }
 
-    if (RenderBlock::hasPercentHeightContainerMap() && firstChild()
+    if (RenderBlock::hasPercentHeightContainerMap() && slowFirstChild()
         && oldHorizontalWritingMode != isHorizontalWritingMode())
         RenderBlock::clearPercentHeightDescendantsFrom(this);
 
@@ -297,7 +297,7 @@ void RenderBox::updateFromStyle()
     if (RuntimeEnabledFeatures::repaintAfterLayoutEnabled() && (boxHasOverflowClip != hasOverflowClip())) {
         // FIXME: This shouldn't be required if we tracked the visual overflow
         // generated by positioned children or self painting layers. crbug.com/345403
-        for (RenderObject* child = firstChild(); child; child = child->nextSibling())
+        for (RenderObject* child = slowFirstChild(); child; child = child->nextSibling())
             child->setShouldDoFullRepaintIfSelfPaintingLayer(true);
     }
 
@@ -311,7 +311,7 @@ void RenderBox::layout()
 {
     ASSERT(needsLayout());
 
-    RenderObject* child = firstChild();
+    RenderObject* child = slowFirstChild();
     if (!child) {
         clearNeedsLayout();
         return;
@@ -1049,7 +1049,7 @@ bool RenderBox::nodeAtPoint(const HitTestRequest& request, HitTestResult& result
     LayoutPoint adjustedLocation = accumulatedOffset + location();
 
     // Check kids first.
-    for (RenderObject* child = lastChild(); child; child = child->previousSibling()) {
+    for (RenderObject* child = slowLastChild(); child; child = child->previousSibling()) {
         if (!child->hasLayer() && child->nodeAtPoint(request, result, locationInContainer, adjustedLocation, action)) {
             updateHitTestResult(result, locationInContainer.point() - toLayoutSize(adjustedLocation));
             return true;
@@ -1077,7 +1077,7 @@ void RenderBox::paint(PaintInfo& paintInfo, const LayoutPoint& paintOffset)
     // default implementation. Just pass paint through to the children
     PaintInfo childInfo(paintInfo);
     childInfo.updatePaintingRootForChildren(this);
-    for (RenderObject* child = firstChild(); child; child = child->nextSibling())
+    for (RenderObject* child = slowFirstChild(); child; child = child->nextSibling())
         child->paint(childInfo, adjustedPaintOffset);
 }
 
@@ -1285,7 +1285,7 @@ bool RenderBox::foregroundIsKnownToBeOpaqueInRect(const LayoutRect& localRect, u
 {
     if (!maxDepthToTest)
         return false;
-    for (RenderObject* child = firstChild(); child; child = child->nextSibling()) {
+    for (RenderObject* child = slowFirstChild(); child; child = child->nextSibling()) {
         if (!child->isBox())
             continue;
         RenderBox* childBox = toRenderBox(child);
@@ -2141,12 +2141,12 @@ static float getMaxWidthListMarker(const RenderBox* renderer)
     ASSERT(renderer->style()->textAutosizingMultiplier() != 1);
 #endif
     float maxWidth = 0;
-    for (RenderObject* child = renderer->firstChild(); child; child = child->nextSibling()) {
+    for (RenderObject* child = renderer->slowFirstChild(); child; child = child->nextSibling()) {
         if (!child->isListItem())
             continue;
 
         RenderBox* listItem = toRenderBox(child);
-        for (RenderObject* itemChild = listItem->firstChild(); itemChild; itemChild = itemChild->nextSibling()) {
+        for (RenderObject* itemChild = listItem->slowFirstChild(); itemChild; itemChild = itemChild->nextSibling()) {
             if (!itemChild->isListMarker())
                 continue;
             RenderBox* itemMarker = toRenderBox(itemChild);
@@ -4019,7 +4019,8 @@ LayoutRect RenderBox::localCaretRect(InlineBox* box, int caretOffset, LayoutUnit
 PositionWithAffinity RenderBox::positionForPoint(const LayoutPoint& point)
 {
     // no children...return this render object's element, if there is one, and offset 0
-    if (!firstChild())
+    RenderObject* firstChild = slowFirstChild();
+    if (!firstChild)
         return createPositionWithAffinity(nonPseudoNode() ? firstPositionInOrBeforeNode(nonPseudoNode()) : Position());
 
     if (isTable() && nonPseudoNode()) {
@@ -4040,8 +4041,8 @@ PositionWithAffinity RenderBox::positionForPoint(const LayoutPoint& point)
     if (isTableRow())
         adjustedPoint.moveBy(location());
 
-    for (RenderObject* renderObject = firstChild(); renderObject; renderObject = renderObject->nextSibling()) {
-        if ((!renderObject->firstChild() && !renderObject->isInline() && !renderObject->isRenderBlockFlow() )
+    for (RenderObject* renderObject = firstChild; renderObject; renderObject = renderObject->nextSibling()) {
+        if ((!renderObject->slowFirstChild() && !renderObject->isInline() && !renderObject->isRenderBlockFlow() )
             || renderObject->style()->visibility() != VISIBLE)
             continue;
 
@@ -4128,7 +4129,7 @@ void RenderBox::markForPaginationRelayoutIfNeeded(SubtreeLayoutScope& layoutScop
     ASSERT(!needsLayout());
     // If fragmentation height has changed, we need to lay out. No need to enter the renderer if it
     // is childless, though.
-    if (view()->layoutState()->pageLogicalHeightChanged() && firstChild())
+    if (view()->layoutState()->pageLogicalHeightChanged() && slowFirstChild())
         layoutScope.setChildNeedsLayout(this);
 }
 
@@ -4644,7 +4645,7 @@ RenderObject* RenderBox::splitAnonymousBoxesAroundChild(RenderObject* beforeChil
 
     while (beforeChild->parent() != this) {
         RenderBox* boxToSplit = toRenderBox(beforeChild->parent());
-        if (boxToSplit->firstChild() != beforeChild && boxToSplit->isAnonymous()) {
+        if (boxToSplit->slowFirstChild() != beforeChild && boxToSplit->isAnonymous()) {
             didSplitParentAnonymousBoxes = true;
 
             // We have to split the parent box into two boxes and move children