https://bugs.webkit.org/show_bug.cgi?id=68922

https://bugs.webkit.org/show_bug.cgi?id=68922

Source/WebCore:

Paginated floats should not grow the height of a block when they don't end
up being tied to a line. Floats encountered in skipLeadingWhitespace that
paginate can't immediately grow the height of the block, since there may not
end up being any actual line content. We only want to push the height of the
block down if we have actual line content that we want to keep with the
float.

Make positionNewFloatOnLine check if the line is empty or not, and if it is,
it just puts the desired pagination strut into LineInfo. If and when actual
line content is encountered and setEmpty becomes false, we'll grow the block
height then.

Reviewed by Dan Bernstein.

Added fast/multicol/float-paginate-empty-lines.html and
fast/regions/webkit-flow-double-pagination-float-push.html.

* rendering/RenderBlock.h:
* rendering/RenderBlockLineLayout.cpp:
(WebCore::LineWidth::LineWidth):
(WebCore::LineWidth::fitsOnLine):
(WebCore::LineWidth::currentWidth):
(WebCore::LineWidth::uncommittedWidth):
(WebCore::LineWidth::committedWidth):
(WebCore::LineWidth::availableWidth):
(WebCore::LineWidth::addUncommittedWidth):
(WebCore::LineWidth::commit):
(WebCore::LineWidth::computeAvailableWidthFromLeftAndRight):
(WebCore::LineWidth::updateAvailableWidth):
(WebCore::LineWidth::shrinkAvailableWidthForNewFloatIfNeeded):
(WebCore::LineWidth::applyOverhang):
(WebCore::LineWidth::fitBelowFloats):
(WebCore::LineInfo::LineInfo):
(WebCore::LineInfo::floatPaginationStrut):
(WebCore::LineInfo::setEmpty):
(WebCore::LineInfo::setFloatPaginationStrut):
(WebCore::RenderBlock::LineBreaker::skipLeadingWhitespace):
(WebCore::RenderBlock::LineBreaker::nextLineBreak):
(WebCore::RenderBlock::positionNewFloatOnLine):

LayoutTests:

Paginated floats should not grow the height of a block when they don't end
up being tied to a line.

Reviewed by Dan Bernstein.

* fast/multicol/float-paginate-empty-lines.html: Added.
* fast/regions/webkit-flow-double-pagination-float-push.html: Added.
* platform/mac/fast/multicol/float-paginate-empty-lines-expected.png: Added.
* platform/mac/fast/regions/webkit-flow-double-pagination-float-push-expected.png: Added.
* platform/mac/fast/regions/webkit-flow-double-pagination-float-push-expected.txt: Added.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@96149 268f45cc-cd09-0410-ab3c-d52691b4dbfc