Move self-collapse checking to LayoutBlockFlow and cache it completely.

third_party/WebKit/Source/core/layout/LayoutBlock.cpp

Index: third_party/WebKit/Source/core/layout/LayoutBlock.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutBlock.cpp b/third_party/WebKit/Source/core/layout/LayoutBlock.cpp
index 375d4a4277ba5116d997db3195fd9481a189da6f..a3f657d18a227fc6664fde0f584770e73d53250a 100644
--- a/third_party/WebKit/Source/core/layout/LayoutBlock.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutBlock.cpp
@@ -117,7 +117,7 @@ LayoutBlock::LayoutBlock(ContainerNode* node)
     , m_hasMarkupTruncation(false)
     , m_widthAvailableToChildrenChanged(false)
     , m_heightAvailableToChildrenChanged(false)
-    , m_hasOnlySelfCollapsingChildren(false)
+    , m_isSelfCollapsing(false)
     , m_descendantsWithFloatsMarkedForLayout(false)
     , m_hasPositionedObjects(false)
     , m_hasPercentHeightDescendants(false)
@@ -747,68 +747,6 @@ void LayoutBlock::removeChild(LayoutObject* oldChild)
     }
 }
 
-bool LayoutBlock::isSelfCollapsingBlock() const
-{
-    // We are not self-collapsing if we
-    // (a) have a non-zero height according to layout (an optimization to avoid wasting time)
-    // (b) are a table,
-    // (c) have border/padding,
-    // (d) have a min-height
-    // (e) have specified that one of our margins can't collapse using a CSS extension
-    // (f) establish a new block formatting context.
-
-    // The early exit must be done before we check for clean layout.
-    // We should be able to give a quick answer if the box is a relayout boundary.
-    // Being a relayout boundary implies a block formatting context, and also
-    // our internal layout shouldn't affect our container in any way.
-    if (createsNewFormattingContext())
-        return false;
-
-    // Placeholder elements are not laid out until the dimensions of their parent text control are known, so they
-    // don't get layout until their parent has had layout - this is unique in the layout tree and means
-    // when we call isSelfCollapsingBlock on them we find that they still need layout.
-    ASSERT(!needsLayout() || (node() && node()->isElementNode() && toElement(node())->shadowPseudoId() == "-webkit-input-placeholder"));
-
-    if (logicalHeight() > 0
-        || isTable() || borderAndPaddingLogicalHeight()
-        || style()->logicalMinHeight().isPositive()
-        || style()->marginBeforeCollapse() == MarginCollapseSeparate || style()->marginAfterCollapse() == MarginCollapseSeparate)
-        return false;
-
-    Length logicalHeightLength = style()->logicalHeight();
-    bool hasAutoHeight = logicalHeightLength.isAuto();
-    if (logicalHeightLength.hasPercent() && !document().inQuirksMode()) {
-        hasAutoHeight = true;
-        for (LayoutBlock* cb = containingBlock(); !cb->isLayoutView(); cb = cb->containingBlock()) {
-            if (cb->style()->logicalHeight().isFixed() || cb->isTableCell())
-                hasAutoHeight = false;
-        }
-    }
-
-    // If the height is 0 or auto, then whether or not we are a self-collapsing block depends
-    // on whether we have content that is all self-collapsing or not.
-    // TODO(alancutter): Make this work correctly for calc lengths.
-    if (hasAutoHeight || ((logicalHeightLength.isFixed() || logicalHeightLength.hasPercent()) && logicalHeightLength.isZero())) {
-        // If the block has inline children, see if we generated any line boxes.  If we have any
-        // line boxes, then we can't be self-collapsing, since we have content.
-        if (childrenInline())
-            return !firstLineBox();
-
-        // Whether or not we collapse is dependent on whether all our normal flow children
-        // are also self-collapsing.
-        if (m_hasOnlySelfCollapsingChildren)
-            return true;
-        for (LayoutBox* child = firstChildBox(); child; child = child->nextSiblingBox()) {
-            if (child->isFloatingOrOutOfFlowPositioned())
-                continue;
-            if (!child->isSelfCollapsingBlock())
-                return false;
-        }
-        return true;
-    }
-    return false;
-}
-
 void LayoutBlock::startDelayUpdateScrollInfo()
 {
     if (gDelayUpdateScrollInfo == 0) {