Remove margin collapsing.

sky/engine/core/rendering/RenderBlockFlow.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 25 matching lines @@
 #include "core/frame/Settings.h"
 #include "core/rendering/HitTestLocation.h"
 #include "core/rendering/RenderLayer.h"
 #include "core/rendering/RenderText.h"
 #include "core/rendering/RenderView.h"
 #include "core/rendering/line/LineWidth.h"
 #include "platform/text/BidiTextRun.h"
 
 namespace blink {
 
-struct SameSizeAsMarginInfo {
-    uint16_t bitfields;
-    LayoutUnit margins[2];
-};
-
-COMPILE_ASSERT(sizeof(RenderBlockFlow::MarginValues) == sizeof(LayoutUnit[4]), MarginValues_should_stay_small);
-
-class MarginInfo {
-    // Collapsing flags for whether we can collapse our margins with our children's margins.
-    bool m_canCollapseWithChildren : 1;
-    bool m_canCollapseMarginBeforeWithChildren : 1;
-    bool m_canCollapseMarginAfterWithChildren : 1;
-    bool m_canCollapseMarginAfterWithLastChild: 1;
-
-    // This flag tracks whether we are still looking at child margins that can all collapse together at the beginning of a block.
-    // They may or may not collapse with the top margin of the block (|m_canCollapseTopWithChildren| tells us that), but they will
-    // always be collapsing with one another. This variable can remain set to true through multiple iterations
-    // as long as we keep encountering self-collapsing blocks.
-    bool m_atBeforeSideOfBlock : 1;
-
-    // This flag is set when we know we're examining bottom margins and we know we're at the bottom of the block.
-    bool m_atAfterSideOfBlock : 1;
-
-    // These variables are used to detect quirky margins that we need to collapse away (in table cells
-    // and in the body element).
-    bool m_hasMarginBeforeQuirk : 1;
-    bool m_hasMarginAfterQuirk : 1;
-    bool m_determinedMarginBeforeQuirk : 1;
-
-    bool m_discardMargin : 1;
-
-    // These flags track the previous maximal positive and negative margins.
-    LayoutUnit m_positiveMargin;
-    LayoutUnit m_negativeMargin;
-
-public:
-    MarginInfo(RenderBlockFlow*, LayoutUnit beforeBorderPadding, LayoutUnit afterBorderPadding);
-
-    void setAtBeforeSideOfBlock(bool b) { m_atBeforeSideOfBlock = b; }
-    void setAtAfterSideOfBlock(bool b) { m_atAfterSideOfBlock = b; }
-    void clearMargin()
-    {
-        m_positiveMargin = 0;
-        m_negativeMargin = 0;
-    }
-    void setHasMarginBeforeQuirk(bool b) { m_hasMarginBeforeQuirk = b; }
-    void setHasMarginAfterQuirk(bool b) { m_hasMarginAfterQuirk = b; }
-    void setDeterminedMarginBeforeQuirk(bool b) { m_determinedMarginBeforeQuirk = b; }
-    void setPositiveMargin(LayoutUnit p) { ASSERT(!m_discardMargin); m_positiveMargin = p; }
-    void setNegativeMargin(LayoutUnit n) { ASSERT(!m_discardMargin); m_negativeMargin = n; }
-    void setPositiveMarginIfLarger(LayoutUnit p)
-    {
-        ASSERT(!m_discardMargin);
-        if (p > m_positiveMargin)
-            m_positiveMargin = p;
-    }
-    void setNegativeMarginIfLarger(LayoutUnit n)
-    {
-        ASSERT(!m_discardMargin);
-        if (n > m_negativeMargin)
-            m_negativeMargin = n;
-    }
-
-    void setMargin(LayoutUnit p, LayoutUnit n) { ASSERT(!m_discardMargin); m_positiveMargin = p; m_negativeMargin = n; }
-    void setCanCollapseMarginAfterWithChildren(bool collapse) { m_canCollapseMarginAfterWithChildren = collapse; }
-    void setCanCollapseMarginAfterWithLastChild(bool collapse) { m_canCollapseMarginAfterWithLastChild = collapse; }
-    void setDiscardMargin(bool value) { m_discardMargin = value; }
-
-    bool atBeforeSideOfBlock() const { return m_atBeforeSideOfBlock; }
-    bool canCollapseWithMarginBefore() const { return m_atBeforeSideOfBlock && m_canCollapseMarginBeforeWithChildren; }
-    bool canCollapseWithMarginAfter() const { return m_atAfterSideOfBlock && m_canCollapseMarginAfterWithChildren; }
-    bool canCollapseMarginBeforeWithChildren() const { return m_canCollapseMarginBeforeWithChildren; }
-    bool canCollapseMarginAfterWithChildren() const { return m_canCollapseMarginAfterWithChildren; }
-    bool canCollapseMarginAfterWithLastChild() const { return m_canCollapseMarginAfterWithLastChild; }
-    bool determinedMarginBeforeQuirk() const { return m_determinedMarginBeforeQuirk; }
-    bool hasMarginBeforeQuirk() const { return m_hasMarginBeforeQuirk; }
-    bool hasMarginAfterQuirk() const { return m_hasMarginAfterQuirk; }
-    LayoutUnit positiveMargin() const { return m_positiveMargin; }
-    LayoutUnit negativeMargin() const { return m_negativeMargin; }
-    bool discardMargin() const { return m_discardMargin; }
-    LayoutUnit margin() const { return m_positiveMargin - m_negativeMargin; }
-};
-
-void RenderBlockFlow::RenderBlockFlowRareData::trace(Visitor* visitor)
-{
-}
-
 RenderBlockFlow::RenderBlockFlow(ContainerNode* node)
     : RenderBlock(node)
 {
-    COMPILE_ASSERT(sizeof(MarginInfo) == sizeof(SameSizeAsMarginInfo), MarginInfo_should_stay_small);
     setChildrenInline(true);
 }
 
 RenderBlockFlow::~RenderBlockFlow()
 {
 }
 
-void RenderBlockFlow::trace(Visitor* visitor)
-{
-    visitor->trace(m_rareData);
-    RenderBlock::trace(visitor);
-}
-
 RenderBlockFlow* RenderBlockFlow::createAnonymous(Document* document)
 {
     RenderBlockFlow* renderer = new RenderBlockFlow(0);
     renderer->setDocumentForAnonymous(document);
     return renderer;
 }
 
 bool RenderBlockFlow::updateLogicalWidthAndColumnWidth()
 {
     return RenderBlock::updateLogicalWidthAndColumnWidth();
 }
 
-bool RenderBlockFlow::isSelfCollapsingBlock() const
-{
-    m_hasOnlySelfCollapsingChildren = RenderBlock::isSelfCollapsingBlock();
-    return m_hasOnlySelfCollapsingChildren;
-}
-
 void RenderBlockFlow::layoutBlock(bool relayoutChildren)
 {
     ASSERT(needsLayout());
     ASSERT(isInlineBlock() || !isInline());
 
-    // If we are self-collapsing with self-collapsing descendants this will get set to save us burrowing through our
-    // descendants every time in |isSelfCollapsingBlock|. We reset it here so that |isSelfCollapsingBlock| attempts to burrow
-    // at least once and so that it always gives a reliable result reflecting the latest layout.
-    m_hasOnlySelfCollapsingChildren = false;
-
     if (!relayoutChildren && simplifiedLayout())
         return;
 
     SubtreeLayoutScope layoutScope(*this);
 
     layoutBlockFlow(relayoutChildren, layoutScope);
 
     updateLayerTransformAfterLayout();
 
     // Update our scroll information if we're overflow:auto/scroll/hidden now that we know if
     // we overflow or not.
     updateScrollInfoAfterLayout();
 
     if (m_paintInvalidationLogicalTop != m_paintInvalidationLogicalBottom)
         setShouldInvalidateOverflowForPaint(true);
 
     clearNeedsLayout();
 }
 
 inline void RenderBlockFlow::layoutBlockFlow(bool relayoutChildren, SubtreeLayoutScope& layoutScope)
 {
     LayoutUnit oldLeft = logicalLeft();
     bool logicalWidthChanged = updateLogicalWidthAndColumnWidth();
     relayoutChildren |= logicalWidthChanged;
 
     LayoutState state(*this, locationOffset(), logicalWidthChanged);
 
-    // We use four values, maxTopPos, maxTopNeg, maxBottomPos, and maxBottomNeg, to track
-    // our current maximal positive and negative margins. These values are used when we
-    // are collapsed with adjacent blocks, so for example, if you have block A and B
-    // collapsing together, then you'd take the maximal positive margin from both A and B
-    // and subtract it from the maximal negative margin from both A and B to get the
-    // true collapsed margin. This algorithm is recursive, so when we finish layout()
-    // our block knows its current maximal positive/negative values.
-    initMaxMarginValues();
-    setHasMarginBeforeQuirk(style()->hasMarginBeforeQuirk());
-    setHasMarginAfterQuirk(style()->hasMarginAfterQuirk());
-
     LayoutUnit beforeEdge = borderBefore() + paddingBefore();
     LayoutUnit afterEdge = borderAfter() + paddingAfter() + scrollbarLogicalHeight();
     LayoutUnit previousHeight = logicalHeight();
     setLogicalHeight(beforeEdge);
 
     m_paintInvalidationLogicalTop = 0;
     m_paintInvalidationLogicalBottom = 0;
     if (!firstChild() && !isAnonymousBlock())
         setChildrenInline(true);
 
@@ skipping 28 matching lines @@
     // If the child has an offset from the content edge to avoid floats then use that, otherwise let any negative
     // margin pull it back over the content edge or any positive margin push it out.
     // If the child is being centred then the margin calculated to do that has factored in any offset required to
     // avoid floats, so use it if necessary.
     if (style()->textAlign() == WEBKIT_CENTER || child->style()->marginStartUsing(style()).isAuto())
         newPosition = std::max(newPosition, childMarginStart);
 
     child->setX(style()->isLeftToRightDirection() ? newPosition : totalAvailableLogicalWidth - newPosition - logicalWidthForChild(child));
 }
 
-void RenderBlockFlow::layoutBlockChild(RenderBox* child, MarginInfo& marginInfo)
+void RenderBlockFlow::layoutBlockChild(RenderBox* child)
 {
-    // The child is a normal flow object. Compute the margins we will use for collapsing now.
     child->computeAndSetBlockDirectionMargins(this);
-
-    // Try to guess our correct logical top position. In most cases this guess will
-    // be correct. Only if we're wrong (when we compute the real logical top position)
-    // will we have to potentially relayout.
-    // Go ahead and position the child as though it didn't collapse with the top.
-    child->setY(estimateLogicalTopPosition(child, marginInfo));
-
+    LayoutUnit marginBefore = marginBeforeForChild(child);
+    child->setY(logicalHeight() + marginBefore);
     child->layoutIfNeeded();
-
-    // Cache if we are at the top of the block right now.
-    bool childIsSelfCollapsing = child->isSelfCollapsingBlock();
-
-    // Now determine the correct ypos based off examination of collapsing margin
-    // values.
-    child->setY(collapseMargins(child, marginInfo, childIsSelfCollapsing));
-
-    // FIXME(sky): Is it still actually possible for the child to need layout here?
-    // This used to be needed for floats and/or margin collapsing.
-    child->layoutIfNeeded();
-
-    // If we previously encountered a self-collapsing sibling of this child that had clearance then
-    // we set this bit to ensure we would not collapse the child's margins, and those of any subsequent
-    // self-collapsing siblings, with our parent. If this child is not self-collapsing then it can
-    // collapse its margins with the parent so reset the bit.
-    if (!marginInfo.canCollapseMarginAfterWithLastChild() && !childIsSelfCollapsing)
-        marginInfo.setCanCollapseMarginAfterWithLastChild(true);
-
-    // We are no longer at the top of the block if we encounter a non-empty child.
-    // This has to be done after checking for clear, so that margins can be reset if a clear occurred.
-    if (marginInfo.atBeforeSideOfBlock() && !childIsSelfCollapsing)
-        marginInfo.setAtBeforeSideOfBlock(false);
-
-    // Now place the child in the correct left position
     determineLogicalLeftPositionForChild(child);
-
-    // Update our height now that the child has been placed in the correct position.
-    setLogicalHeight(logicalHeight() + logicalHeightForChild(child));
-    if (mustSeparateMarginAfterForChild(child)) {
-        setLogicalHeight(logicalHeight() + marginAfterForChild(child));
-        marginInfo.clearMargin();
-    }
+    setLogicalHeight(logicalHeight() + marginBefore + logicalHeightForChild(child) + marginAfterForChild(child));
 }
 
 void RenderBlockFlow::layoutBlockChildren(bool relayoutChildren, SubtreeLayoutScope& layoutScope, LayoutUnit beforeEdge, LayoutUnit afterEdge)
 {
     dirtyForLayoutFromPercentageHeightDescendants(layoutScope);
 
-    // The margin struct caches all our current margin collapsing state. The compact struct caches state when we encounter compacts,
-    MarginInfo marginInfo(this, beforeEdge, afterEdge);
-
     RenderBox* next = firstChildBox();
     RenderBox* lastNormalFlowChild = 0;
 
     while (next) {
         RenderBox* child = next;
         next = child->nextSiblingBox();
 
         // FIXME: this should only be set from clearNeedsLayout crbug.com/361250
         child->setLayoutDidGetCalled(true);
 
         updateBlockChildDirtyBitsBeforeLayout(relayoutChildren, child);
 
         if (child->isOutOfFlowPositioned()) {
             child->containingBlock()->insertPositionedObject(child);
-            adjustPositionedBlock(child, marginInfo);
+            adjustPositionedBlock(child);
             continue;
         }
 
         // Lay out the child.
-        layoutBlockChild(child, marginInfo);
+        layoutBlockChild(child);
         lastNormalFlowChild = child;
     }
 
-    // Now do the handling of the bottom of the block, adding in our bottom border/padding and
-    // determining the correct collapsed bottom margin information.
-    handleAfterSideOfBlock(lastNormalFlowChild, beforeEdge, afterEdge, marginInfo);
+    // Negative margins can cause our height to shrink below our minimal height (border/padding).
+    // If this happens, ensure that the computed height is increased to the minimal height.
+    setLogicalHeight(std::max(logicalHeight() + afterEdge, beforeEdge + afterEdge));
 }
 
-// Our MarginInfo state used when laying out block children.
-MarginInfo::MarginInfo(RenderBlockFlow* blockFlow, LayoutUnit beforeBorderPadding, LayoutUnit afterBorderPadding)
-    : m_canCollapseMarginAfterWithLastChild(true)
-    , m_atBeforeSideOfBlock(true)
-    , m_atAfterSideOfBlock(false)
-    , m_hasMarginBeforeQuirk(false)
-    , m_hasMarginAfterQuirk(false)
-    , m_determinedMarginBeforeQuirk(false)
-    , m_discardMargin(false)
-{
-    RenderStyle* blockStyle = blockFlow->style();
-    ASSERT(blockFlow->isRenderView() || blockFlow->parent());
-    m_canCollapseWithChildren = !blockFlow->createsBlockFormattingContext() && !blockFlow->isRenderView();
-
-    m_canCollapseMarginBeforeWithChildren = m_canCollapseWithChildren && !beforeBorderPadding && blockStyle->marginBeforeCollapse() != MSEPARATE;
-
-    // If any height other than auto is specified in CSS, then we don't collapse our bottom
-    // margins with our children's margins. To do otherwise would be to risk odd visual
-    // effects when the children overflow out of the parent block and yet still collapse
-    // with it. We also don't collapse if we have any bottom border/padding.
-    m_canCollapseMarginAfterWithChildren = m_canCollapseWithChildren && !afterBorderPadding
-        && (blockStyle->logicalHeight().isAuto() && !blockStyle->logicalHeight().value()) && blockStyle->marginAfterCollapse() != MSEPARATE;
-
-    m_discardMargin = m_canCollapseMarginBeforeWithChildren && blockFlow->mustDiscardMarginBefore();
-
-    m_positiveMargin = (m_canCollapseMarginBeforeWithChildren && !blockFlow->mustDiscardMarginBefore()) ? blockFlow->maxPositiveMarginBefore() : LayoutUnit();
-    m_negativeMargin = (m_canCollapseMarginBeforeWithChildren && !blockFlow->mustDiscardMarginBefore()) ? blockFlow->maxNegativeMarginBefore() : LayoutUnit();
-}
-
-RenderBlockFlow::MarginValues RenderBlockFlow::marginValuesForChild(RenderBox* child) const
-{
-    LayoutUnit childBeforePositive = 0;
-    LayoutUnit childBeforeNegative = 0;
-    LayoutUnit childAfterPositive = 0;
-    LayoutUnit childAfterNegative = 0;
-
-    LayoutUnit beforeMargin = 0;
-    LayoutUnit afterMargin = 0;
-
-    RenderBlockFlow* childRenderBlockFlow = child->isRenderBlockFlow() ? toRenderBlockFlow(child) : 0;
-
-    if (childRenderBlockFlow) {
-        childBeforePositive = childRenderBlockFlow->maxPositiveMarginBefore();
-        childBeforeNegative = childRenderBlockFlow->maxNegativeMarginBefore();
-        childAfterPositive = childRenderBlockFlow->maxPositiveMarginAfter();
-        childAfterNegative = childRenderBlockFlow->maxNegativeMarginAfter();
-    } else {
-        beforeMargin = child->marginBefore();
-        afterMargin = child->marginAfter();
-    }
-
-    // Resolve uncollapsing margins into their positive/negative buckets.
-    if (beforeMargin) {
-        if (beforeMargin > 0)
-            childBeforePositive = beforeMargin;
-        else
-            childBeforeNegative = -beforeMargin;
-    }
-    if (afterMargin) {
-        if (afterMargin > 0)
-            childAfterPositive = afterMargin;
-        else
-            childAfterNegative = -afterMargin;
-    }
-
-    return RenderBlockFlow::MarginValues(childBeforePositive, childBeforeNegative, childAfterPositive, childAfterNegative);
-}
-
-LayoutUnit RenderBlockFlow::collapseMargins(RenderBox* child, MarginInfo& marginInfo, bool childIsSelfCollapsing)
-{
-    bool childDiscardMarginBefore = mustDiscardMarginBeforeForChild(child);
-    bool childDiscardMarginAfter = mustDiscardMarginAfterForChild(child);
-
-    // The child discards the before margin when the the after margin has discard in the case of a self collapsing block.
-    childDiscardMarginBefore = childDiscardMarginBefore || (childDiscardMarginAfter && childIsSelfCollapsing);
-
-    // Get the four margin values for the child and cache them.
-    const RenderBlockFlow::MarginValues childMargins = marginValuesForChild(child);
-
-    // Get our max pos and neg top margins.
-    LayoutUnit posTop = childMargins.positiveMarginBefore();
-    LayoutUnit negTop = childMargins.negativeMarginBefore();
-
-    // For self-collapsing blocks, collapse our bottom margins into our
-    // top to get new posTop and negTop values.
-    if (childIsSelfCollapsing) {
-        posTop = std::max(posTop, childMargins.positiveMarginAfter());
-        negTop = std::max(negTop, childMargins.negativeMarginAfter());
-    }
-
-    // See if the top margin is quirky. We only care if this child has
-    // margins that will collapse with us.
-    bool topQuirk = hasMarginBeforeQuirk(child);
-
-    if (marginInfo.canCollapseWithMarginBefore()) {
-        if (!childDiscardMarginBefore && !marginInfo.discardMargin()) {
-            // This child is collapsing with the top of the
-            // block. If it has larger margin values, then we need to update
-            // our own maximal values.
-            setMaxMarginBeforeValues(std::max(posTop, maxPositiveMarginBefore()), std::max(negTop, maxNegativeMarginBefore()));
-
-            // The minute any of the margins involved isn't a quirk, don't
-            // collapse it away, even if the margin is smaller (www.webreference.com
-            // has an example of this, a <dt> with 0.8em author-specified inside
-            // a <dl> inside a <td>.
-            if (!marginInfo.determinedMarginBeforeQuirk() && !topQuirk && (posTop - negTop)) {
-                setHasMarginBeforeQuirk(false);
-                marginInfo.setDeterminedMarginBeforeQuirk(true);
-            }
-
-            if (!marginInfo.determinedMarginBeforeQuirk() && topQuirk && !marginBefore()) {
-                // We have no top margin and our top child has a quirky margin.
-                // We will pick up this quirky margin and pass it through.
-                // This deals with the <td><div><p> case.
-                // Don't do this for a block that split two inlines though. You do
-                // still apply margins in this case.
-                setHasMarginBeforeQuirk(true);
-            }
-        } else {
-            // The before margin of the container will also discard all the margins it is collapsing with.
-            setMustDiscardMarginBefore();
-        }
-    }
-
-    // Once we find a child with discardMarginBefore all the margins collapsing with us must also discard.
-    if (childDiscardMarginBefore) {
-        marginInfo.setDiscardMargin(true);
-        marginInfo.clearMargin();
-    }
-
-    LayoutUnit beforeCollapseLogicalTop = logicalHeight();
-    LayoutUnit logicalTop = beforeCollapseLogicalTop;
-
-    LayoutUnit clearanceForSelfCollapsingBlock;
-    RenderObject* prev = child->previousSibling();
-    RenderBlockFlow* previousBlockFlow =  prev && prev->isRenderBlockFlow() && !prev->isFloatingOrOutOfFlowPositioned() ? toRenderBlockFlow(prev) : 0;
-    // If the child's previous sibling is a self-collapsing block that cleared a float then its top border edge has been set at the bottom border edge
-    // of the float. Since we want to collapse the child's top margin with the self-collapsing block's top and bottom margins we need to adjust our parent's height to match the
-    // margin top of the self-collapsing block. If the resulting collapsed margin leaves the child still intruding into the float then we will want to clear it.
-    if (!marginInfo.canCollapseWithMarginBefore() && previousBlockFlow && previousBlockFlow->isSelfCollapsingBlock()) {
-        clearanceForSelfCollapsingBlock = previousBlockFlow->marginOffsetForSelfCollapsingBlock();
-        setLogicalHeight(logicalHeight() - clearanceForSelfCollapsingBlock);
-    }
-
-    if (childIsSelfCollapsing) {
-        // For a self collapsing block both the before and after margins get discarded. The block doesn't contribute anything to the height of the block.
-        // Also, the child's top position equals the logical height of the container.
-        if (!childDiscardMarginBefore && !marginInfo.discardMargin()) {
-            // This child has no height. We need to compute our
-            // position before we collapse the child's margins together,
-            // so that we can get an accurate position for the zero-height block.
-            LayoutUnit collapsedBeforePos = std::max(marginInfo.positiveMargin(), childMargins.positiveMarginBefore());
-            LayoutUnit collapsedBeforeNeg = std::max(marginInfo.negativeMargin(), childMargins.negativeMarginBefore());
-            marginInfo.setMargin(collapsedBeforePos, collapsedBeforeNeg);
-
-            // Now collapse the child's margins together, which means examining our
-            // bottom margin values as well.
-            marginInfo.setPositiveMarginIfLarger(childMargins.positiveMarginAfter());
-            marginInfo.setNegativeMarginIfLarger(childMargins.negativeMarginAfter());
-
-            if (!marginInfo.canCollapseWithMarginBefore()) {
-                // We need to make sure that the position of the self-collapsing block
-                // is correct, since it could have overflowing content
-                // that needs to be positioned correctly (e.g., a block that
-                // had a specified height of 0 but that actually had subcontent).
-                logicalTop = logicalHeight() + collapsedBeforePos - collapsedBeforeNeg;
-            }
-        }
-    } else {
-        if (mustSeparateMarginBeforeForChild(child)) {
-            ASSERT(!marginInfo.discardMargin() || (marginInfo.discardMargin() && !marginInfo.margin()));
-            // If we are at the before side of the block and we collapse, ignore the computed margin
-            // and just add the child margin to the container height. This will correctly position
-            // the child inside the container.
-            LayoutUnit separateMargin = !marginInfo.canCollapseWithMarginBefore() ? marginInfo.margin() : LayoutUnit(0);
-            setLogicalHeight(logicalHeight() + separateMargin + marginBeforeForChild(child));
-            logicalTop = logicalHeight();
-        } else if (!marginInfo.discardMargin() && (!marginInfo.atBeforeSideOfBlock()
-            || (!marginInfo.canCollapseMarginBeforeWithChildren()))) {
-            // We're collapsing with a previous sibling's margins and not
-            // with the top of the block.
-            setLogicalHeight(logicalHeight() + std::max(marginInfo.positiveMargin(), posTop) - std::max(marginInfo.negativeMargin(), negTop));
-            logicalTop = logicalHeight();
-        }
-
-        marginInfo.setDiscardMargin(childDiscardMarginAfter);
-
-        if (!marginInfo.discardMargin()) {
-            marginInfo.setPositiveMargin(childMargins.positiveMarginAfter());
-            marginInfo.setNegativeMargin(childMargins.negativeMarginAfter());
-        } else {
-            marginInfo.clearMargin();
-        }
-
-        if (marginInfo.margin())
-            marginInfo.setHasMarginAfterQuirk(hasMarginAfterQuirk(child));
-    }
-
-    return logicalTop;
-}
-
-void RenderBlockFlow::adjustPositionedBlock(RenderBox* child, const MarginInfo& marginInfo)
+void RenderBlockFlow::adjustPositionedBlock(RenderBox* child)
 {
     bool hasStaticBlockPosition = child->style()->hasStaticBlockPosition();
 
     LayoutUnit logicalTop = logicalHeight();
     updateStaticInlinePositionForChild(child, logicalTop);
 
-    if (!marginInfo.canCollapseWithMarginBefore()) {
-        // Positioned blocks don't collapse margins, so add the margin provided by
-        // the container now. The child's own margin is added later when calculating its logical top.
-        LayoutUnit collapsedBeforePos = marginInfo.positiveMargin();
-        LayoutUnit collapsedBeforeNeg = marginInfo.negativeMargin();
-        logicalTop += collapsedBeforePos - collapsedBeforeNeg;
-    }
-
     RenderLayer* childLayer = child->layer();
     if (childLayer->staticBlockPosition() != logicalTop) {
         childLayer->setStaticBlockPosition(logicalTop);
         if (hasStaticBlockPosition)
             child->setChildNeedsLayout(MarkOnlyThis);
     }
 }
 
-void RenderBlockFlow::setCollapsedBottomMargin(const MarginInfo& marginInfo)
-{
-    if (marginInfo.canCollapseWithMarginAfter() && !marginInfo.canCollapseWithMarginBefore()) {
-        // Update the after side margin of the container to discard if the after margin of the last child also discards and we collapse with it.
-        // Don't update the max margin values because we won't need them anyway.
-        if (marginInfo.discardMargin()) {
-            setMustDiscardMarginAfter();
-            return;
-        }
-
-        // Update our max pos/neg bottom margins, since we collapsed our bottom margins
-        // with our children.
-        setMaxMarginAfterValues(std::max(maxPositiveMarginAfter(), marginInfo.positiveMargin()), std::max(maxNegativeMarginAfter(), marginInfo.negativeMargin()));
-
-        if (!marginInfo.hasMarginAfterQuirk())
-            setHasMarginAfterQuirk(false);
-
-        if (marginInfo.hasMarginAfterQuirk() && !marginAfter()) {
-            // We have no bottom margin and our last child has a quirky margin.
-            // We will pick up this quirky margin and pass it through.
-            // This deals with the <td><div><p> case.
-            setHasMarginAfterQuirk(true);
-        }
-    }
-}
-
-void RenderBlockFlow::marginBeforeEstimateForChild(RenderBox* child, LayoutUnit& positiveMarginBefore, LayoutUnit& negativeMarginBefore, bool& discardMarginBefore) const
-{
-    // Give up if in quirks mode and we're a body/table cell and the top margin of the child box is quirky.
-    // Give up if the child specified -webkit-margin-collapse: separate that prevents collapsing.
-    // FIXME: Use writing mode independent accessor for marginBeforeCollapse.
-    if (child->style()->marginBeforeCollapse() == MSEPARATE)
-        return;
-
-    // The margins are discarded by a child that specified -webkit-margin-collapse: discard.
-    // FIXME: Use writing mode independent accessor for marginBeforeCollapse.
-    if (child->style()->marginBeforeCollapse() == MDISCARD) {
-        positiveMarginBefore = 0;
-        negativeMarginBefore = 0;
-        discardMarginBefore = true;
-        return;
-    }
-
-    LayoutUnit beforeChildMargin = marginBeforeForChild(child);
-    positiveMarginBefore = std::max(positiveMarginBefore, beforeChildMargin);
-    negativeMarginBefore = std::max(negativeMarginBefore, -beforeChildMargin);
-
-    if (!child->isRenderBlockFlow())
-        return;
-
-    RenderBlockFlow* childBlockFlow = toRenderBlockFlow(child);
-    if (childBlockFlow->childrenInline())
-        return;
-
-    MarginInfo childMarginInfo(childBlockFlow, childBlockFlow->borderBefore() + childBlockFlow->paddingBefore(), childBlockFlow->borderAfter() + childBlockFlow->paddingAfter());
-    if (!childMarginInfo.canCollapseMarginBeforeWithChildren())
-        return;
-
-    RenderBox* grandchildBox = childBlockFlow->firstChildBox();
-    for ( ; grandchildBox; grandchildBox = grandchildBox->nextSiblingBox()) {
-        if (!grandchildBox->isFloatingOrOutOfFlowPositioned())
-            break;
-    }
-
-    if (!grandchildBox)
-        return;
-
-    // Make sure to update the block margins now for the grandchild box so that we're looking at current values.
-    if (grandchildBox->needsLayout()) {
-        grandchildBox->computeAndSetBlockDirectionMargins(this);
-        if (grandchildBox->isRenderBlock()) {
-            RenderBlock* grandchildBlock = toRenderBlock(grandchildBox);
-            grandchildBlock->setHasMarginBeforeQuirk(grandchildBox->style()->hasMarginBeforeQuirk());
-            grandchildBlock->setHasMarginAfterQuirk(grandchildBox->style()->hasMarginAfterQuirk());
-        }
-    }
-
-    // Collapse the margin of the grandchild box with our own to produce an estimate.
-    childBlockFlow->marginBeforeEstimateForChild(grandchildBox, positiveMarginBefore, negativeMarginBefore, discardMarginBefore);
-}
-
-LayoutUnit RenderBlockFlow::estimateLogicalTopPosition(RenderBox* child, const MarginInfo& marginInfo)
-{
-    // FIXME: We need to eliminate the estimation of vertical position, because when it's wrong we sometimes trigger a pathological
-    // relayout if there are intruding floats.
-    LayoutUnit logicalTopEstimate = logicalHeight();
-    if (!marginInfo.canCollapseWithMarginBefore()) {
-        LayoutUnit positiveMarginBefore = 0;
-        LayoutUnit negativeMarginBefore = 0;
-        bool discardMarginBefore = false;
-        if (child->selfNeedsLayout()) {
-            // Try to do a basic estimation of how the collapse is going to go.
-            marginBeforeEstimateForChild(child, positiveMarginBefore, negativeMarginBefore, discardMarginBefore);
-        } else {
-            // Use the cached collapsed margin values from a previous layout. Most of the time they
-            // will be right.
-            RenderBlockFlow::MarginValues marginValues = marginValuesForChild(child);
-            positiveMarginBefore = std::max(positiveMarginBefore, marginValues.positiveMarginBefore());
-            negativeMarginBefore = std::max(negativeMarginBefore, marginValues.negativeMarginBefore());
-            discardMarginBefore = mustDiscardMarginBeforeForChild(child);
-        }
-
-        // Collapse the result with our current margins.
-        if (!discardMarginBefore)
-            logicalTopEstimate += std::max(marginInfo.positiveMargin(), positiveMarginBefore) - std::max(marginInfo.negativeMargin(), negativeMarginBefore);
-    }
-
-    return logicalTopEstimate;
-}
-
-LayoutUnit RenderBlockFlow::marginOffsetForSelfCollapsingBlock()
-{
-    // FIXME(sky): Remove
-    ASSERT(isSelfCollapsingBlock());
-    return LayoutUnit();
-}
-
-void RenderBlockFlow::handleAfterSideOfBlock(RenderBox* lastChild, LayoutUnit beforeSide, LayoutUnit afterSide, MarginInfo& marginInfo)
-{
-    marginInfo.setAtAfterSideOfBlock(true);
-
-    // If our last child was a self-collapsing block with clearance then our logical height is flush with the
-    // bottom edge of the float that the child clears. The correct vertical position for the margin-collapsing we want
-    // to perform now is at the child's margin-top - so adjust our height to that position.
-    if (lastChild && lastChild->isRenderBlockFlow() && lastChild->isSelfCollapsingBlock())
-        setLogicalHeight(logicalHeight() - toRenderBlockFlow(lastChild)->marginOffsetForSelfCollapsingBlock());
-
-    if (marginInfo.canCollapseMarginAfterWithChildren() && !marginInfo.canCollapseMarginAfterWithLastChild())
-        marginInfo.setCanCollapseMarginAfterWithChildren(false);
-
-    // If we can't collapse with children then go ahead and add in the bottom margin.
-    if (!marginInfo.discardMargin() && (!marginInfo.canCollapseWithMarginAfter() && !marginInfo.canCollapseWithMarginBefore()))
-        setLogicalHeight(logicalHeight() + marginInfo.margin());
-
-    // Now add in our bottom border/padding.
-    setLogicalHeight(logicalHeight() + afterSide);
-
-    // Negative margins can cause our height to shrink below our minimal height (border/padding).
-    // If this happens, ensure that the computed height is increased to the minimal height.
-    setLogicalHeight(std::max(logicalHeight(), beforeSide + afterSide));
-
-    // Update our bottom collapsed margin info.
-    setCollapsedBottomMargin(marginInfo);
-}
-
-void RenderBlockFlow::setMustDiscardMarginBefore(bool value)
-{
-    if (style()->marginBeforeCollapse() == MDISCARD) {
-        ASSERT(value);
-        return;
-    }
-
-    if (!m_rareData && !value)
-        return;
-
-    if (!m_rareData)
-        m_rareData = adoptPtr(new RenderBlockFlowRareData(this));
-
-    m_rareData->m_discardMarginBefore = value;
-}
-
-void RenderBlockFlow::setMustDiscardMarginAfter(bool value)
-{
-    if (style()->marginAfterCollapse() == MDISCARD) {
-        ASSERT(value);
-        return;
-    }
-
-    if (!m_rareData && !value)
-        return;
-
-    if (!m_rareData)
-        m_rareData = adoptPtr(new RenderBlockFlowRareData(this));
-
-    m_rareData->m_discardMarginAfter = value;
-}
-
-bool RenderBlockFlow::mustDiscardMarginBefore() const
-{
-    return style()->marginBeforeCollapse() == MDISCARD || (m_rareData && m_rareData->m_discardMarginBefore);
-}
-
-bool RenderBlockFlow::mustDiscardMarginAfter() const
-{
-    return style()->marginAfterCollapse() == MDISCARD || (m_rareData && m_rareData->m_discardMarginAfter);
-}
-
-bool RenderBlockFlow::mustDiscardMarginBeforeForChild(const RenderBox* child) const
-{
-    ASSERT(!child->selfNeedsLayout());
-    return child->isRenderBlockFlow() ? toRenderBlockFlow(child)->mustDiscardMarginBefore() : (child->style()->marginBeforeCollapse() == MDISCARD);
-}
-
-bool RenderBlockFlow::mustDiscardMarginAfterForChild(const RenderBox* child) const
-{
-    ASSERT(!child->selfNeedsLayout());
-    return child->isRenderBlockFlow() ? toRenderBlockFlow(child)->mustDiscardMarginAfter() : (child->style()->marginAfterCollapse() == MDISCARD);
-}
-
-void RenderBlockFlow::setMaxMarginBeforeValues(LayoutUnit pos, LayoutUnit neg)
-{
-    if (!m_rareData) {
-        if (pos == RenderBlockFlowRareData::positiveMarginBeforeDefault(this) && neg == RenderBlockFlowRareData::negativeMarginBeforeDefault(this))
-            return;
-        m_rareData = adoptPtr(new RenderBlockFlowRareData(this));
-    }
-    m_rareData->m_margins.setPositiveMarginBefore(pos);
-    m_rareData->m_margins.setNegativeMarginBefore(neg);
-}
-
-void RenderBlockFlow::setMaxMarginAfterValues(LayoutUnit pos, LayoutUnit neg)
-{
-    if (!m_rareData) {
-        if (pos == RenderBlockFlowRareData::positiveMarginAfterDefault(this) && neg == RenderBlockFlowRareData::negativeMarginAfterDefault(this))
-            return;
-        m_rareData = adoptPtr(new RenderBlockFlowRareData(this));
-    }
-    m_rareData->m_margins.setPositiveMarginAfter(pos);
-    m_rareData->m_margins.setNegativeMarginAfter(neg);
-}
-
-bool RenderBlockFlow::mustSeparateMarginBeforeForChild(const RenderBox* child) const
-{
-    ASSERT(!child->selfNeedsLayout());
-    const RenderStyle* childStyle = child->style();
-    return childStyle->marginBeforeCollapse() == MSEPARATE;
-}
-
-bool RenderBlockFlow::mustSeparateMarginAfterForChild(const RenderBox* child) const
-{
-    ASSERT(!child->selfNeedsLayout());
-    const RenderStyle* childStyle = child->style();
-    return childStyle->marginAfterCollapse() == MSEPARATE;
-}
-
 RootInlineBox* RenderBlockFlow::createAndAppendRootInlineBox()
 {
     RootInlineBox* rootBox = createRootInlineBox();
     m_lineBoxes.appendLineBox(rootBox);
 
     return rootBox;
 }
 
 void RenderBlockFlow::deleteLineBoxTree()
 {
@@ skipping 199 matching lines @@
         cb = cb->containingBlock();
     }
     return logicalRight;
 }
 
 RootInlineBox* RenderBlockFlow::createRootInlineBox()
 {
     return new RootInlineBox(*this);
 }
 
-RenderBlockFlow::RenderBlockFlowRareData& RenderBlockFlow::ensureRareData()
-{
-    if (m_rareData)
-        return *m_rareData;
-
-    m_rareData = adoptPtr(new RenderBlockFlowRareData(this));
-    return *m_rareData;
-}
-
 } // namespace blink