Self-collapsing block gets layout set during margin collapsing

Source/core/layout/LayoutBlockFlow.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 530 matching lines @@
     if (!child.needsLayout())
         child.markForPaginationRelayoutIfNeeded(layoutScope);
 
     bool childNeededLayout = child.needsLayout();
     if (childNeededLayout)
         child.layout();
 
     // Cache if we are at the top of the block right now.
     bool atBeforeSideOfBlock = marginInfo.atBeforeSideOfBlock();
     bool childIsSelfCollapsing = child.isSelfCollapsingBlock();
+    bool childDiscardMarginBefore = mustDiscardMarginBeforeForChild(child);
+    bool childDiscardMarginAfter = mustDiscardMarginAfterForChild(child);
 
     // Now determine the correct ypos based off examination of collapsing margin
     // values.
-    LayoutUnit logicalTopBeforeClear = collapseMargins(child, marginInfo, childIsSelfCollapsing);
+    LayoutUnit logicalTopBeforeClear = collapseMargins(child, marginInfo, childIsSelfCollapsing, childDiscardMarginBefore, childDiscardMarginAfter);
 
     // Now check for clear.
-    LayoutUnit logicalTopAfterClear = clearFloatsIfNeeded(child, marginInfo, oldPosMarginBefore, oldNegMarginBefore, logicalTopBeforeClear, childIsSelfCollapsing);
+    bool childDiscardMargin = childDiscardMarginBefore || childDiscardMarginAfter;
+    LayoutUnit logicalTopAfterClear = clearFloatsIfNeeded(child, marginInfo, oldPosMarginBefore, oldNegMarginBefore, logicalTopBeforeClear, childIsSelfCollapsing, childDiscardMargin);
 
     bool paginated = view()->layoutState()->isPaginated();
     if (paginated) {
         logicalTopAfterClear = adjustBlockChildForPagination(logicalTopAfterClear, estimateWithoutPagination, child,
             atBeforeSideOfBlock && logicalTopBeforeClear == logicalTopAfterClear);
     }
 
     setLogicalTopForChild(child, logicalTopAfterClear);
 
     // Now we have a final top position. See if it really does end up being different from our estimate.
@@ skipping 547 matching lines @@
     if (afterMargin) {
         if (afterMargin > 0)
             childAfterPositive = afterMargin;
         else
             childAfterNegative = -afterMargin;
     }
 
     return LayoutBlockFlow::MarginValues(childBeforePositive, childBeforeNegative, childAfterPositive, childAfterNegative);
 }
 
-LayoutUnit LayoutBlockFlow::collapseMargins(LayoutBox& child, MarginInfo& marginInfo, bool childIsSelfCollapsing)
+LayoutUnit LayoutBlockFlow::collapseMargins(LayoutBox& child, MarginInfo& marginInfo, bool childIsSelfCollapsing, bool childDiscardMarginBefore, bool childDiscardMarginAfter)
 {
-    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 LayoutBlockFlow::MarginValues childMargins = marginValuesForChild(child);
 
     // Get our max pos and neg top margins.
     LayoutUnit posTop = childMargins.positiveMarginBefore();
     LayoutUnit negTop = childMargins.negativeMarginBefore();
 
@@ skipping 158 matching lines @@
         LayoutUnit collapsedBeforeNeg = marginInfo.negativeMargin();
         logicalTop += collapsedBeforePos - collapsedBeforeNeg;
     }
 
     DeprecatedPaintLayer* childLayer = child.layer();
     if (childLayer->staticBlockPosition() != logicalTop) {
         childLayer->setStaticBlockPosition(logicalTop);
     }
 }
 
-LayoutUnit LayoutBlockFlow::clearFloatsIfNeeded(LayoutBox& child, MarginInfo& marginInfo, LayoutUnit oldTopPosMargin, LayoutUnit oldTopNegMargin, LayoutUnit yPos, bool childIsSelfCollapsing)
+LayoutUnit LayoutBlockFlow::clearFloatsIfNeeded(LayoutBox& child, MarginInfo& marginInfo, LayoutUnit oldTopPosMargin, LayoutUnit oldTopNegMargin, LayoutUnit yPos, bool childIsSelfCollapsing, bool childDiscardMargin)
 {
     LayoutUnit heightIncrease = getClearDelta(&child, yPos);
     marginInfo.setLastChildIsSelfCollapsingBlockWithClearance(false);
 
     if (!heightIncrease)
         return yPos;
 
     if (childIsSelfCollapsing) {
         marginInfo.setLastChildIsSelfCollapsingBlockWithClearance(true);
-        bool childDiscardMargin = mustDiscardMarginBeforeForChild(child) || mustDiscardMarginAfterForChild(child);
         marginInfo.setDiscardMargin(childDiscardMargin);
 
         // For self-collapsing blocks that clear, they can still collapse their
         // margins with following siblings. Reset the current margins to represent
         // the self-collapsing block's margins only.
         // If DISCARD is specified for -webkit-margin-collapse, reset the margin values.
         LayoutBlockFlow::MarginValues childMargins = marginValuesForChild(child);
         if (!childDiscardMargin) {
             marginInfo.setPositiveMargin(std::max(childMargins.positiveMarginBefore(), childMargins.positiveMarginAfter()));
             marginInfo.setNegativeMargin(std::max(childMargins.negativeMarginBefore(), childMargins.negativeMarginAfter()));
@@ skipping 1744 matching lines @@
     FrameView* frameView = document().view();
     LayoutUnit top = (style()->position() == FixedPosition) ? 0 : frameView->scrollOffset().height();
     int visibleHeight = frameView->visibleContentRect(IncludeScrollbars).height();
     if (size().height() < visibleHeight)
         top += (visibleHeight - size().height()) / 2;
     setY(top);
     dialog->setCentered(top);
 }
 
 } // namespace blink