BR styled clear is ignored while partially relayouting.

Source/core/layout/LayoutBlockFlowLine.cpp

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2003, 2004, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All right reserved.
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 1545 matching lines @@
         // the replaced elements later. In partial layout mode, line boxes are not
         // deleted and only dirtied. In that case, we can layout the replaced
         // elements at the same time.
         Vector<LayoutBox*> replacedChildren;
         for (InlineWalker walker(this); !walker.atEnd(); walker.advance()) {
             LayoutObject* o = walker.current();
 
             if (!layoutState.hasInlineChild() && o->isInline())
                 layoutState.setHasInlineChild(true);
 
+            if (o->isBR() && o->style()->clear() != CNONE)

[leviw_travelin_and_unemployed, 2015/05/14 02:22:19]

It's sad that we're doing this whenever there's any br with a clear, not only if
they're in the end of the line.

That said, I think this patch is unintrusive enough as to be okay.

[changseok, 2015/05/14 16:18:46]

Yeah.. Do you have any better idea to reduce iteration? I always welcome a neat
idea. =)

+                layoutState.setContainsBRWithClear(true);
+
             if (o->isReplaced() || o->isFloating() || o->isOutOfFlowPositioned()) {
                 LayoutBox* box = toLayoutBox(o);
 
                 updateBlockChildDirtyBitsBeforeLayout(relayoutChildren, *box);
 
                 if (o->isOutOfFlowPositioned()) {
                     o->containingBlock()->insertPositionedObject(box);
                 } else if (o->isFloating()) {
                     layoutState.floats().append(FloatWithRect(box));
                 } else if (isFullLayout || o->needsLayout()) {
@@ skipping 273 matching lines @@
         if (logicalBottomForFloat(floatingObject) >= logicalTop && logicalBottomForFloat(floatingObject) < logicalBottom)
             return false;
     }
 
     return true;
 }
 
 bool LayoutBlockFlow::matchedEndLine(LineLayoutState& layoutState, const InlineBidiResolver& resolver, const InlineIterator& endLineStart, const BidiStatus& endLineStatus)
 {
     if (resolver.position() == endLineStart) {
-        if (resolver.status() != endLineStatus)
+        if (resolver.status() != endLineStatus || (containsFloats() && layoutState.containsBRWithClear()))

[leviw_travelin_and_unemployed, 2015/05/14 02:22:19]

I think I'd prefer the following:

if (resolver.status() != endLineStatus)
     return false;

// Comment about why we're doing this
if (layoutState.containsBRWithClear() && containsFloats())
    return false;

You'll notice I reversed the order of these because I suspect containing br's
with clear is less common than floats.

[changseok, 2015/05/14 16:18:46]

Make sense.

             return false;
         return checkPaginationAndFloatsAtEndLine(layoutState);
     }
 
     // The first clean line doesn't match, but we can check a handful of following lines to try
     // to match back up.
     static int numLines = 8; // The # of lines we're willing to match against.
     RootInlineBox* originalEndLine = layoutState.endLine();
     RootInlineBox* line = originalEndLine;
     for (int i = 0; i < numLines && line; i++, line = line->nextRootBox()) {
@@ skipping 181 matching lines @@
     float logicalLeft = logicalLeftOffsetForLine(logicalHeight(), false).toFloat();
     float availableLogicalWidth = logicalRightOffsetForLine(logicalHeight(), false) - logicalLeft;
     updateLogicalWidthForAlignment(textAlign, 0, 0, logicalLeft, totalLogicalWidth, availableLogicalWidth, 0);
 
     if (!style()->isLeftToRightDirection())
         return logicalWidth() - logicalLeft;
     return logicalLeft;
 }
 
 }