Remove LayoutFlowThread stuff from line layout code.

Remove LayoutFlowThread stuff from line layout code.

We used to force full line layout if we had a flow thread with no column sets.
This may have made sense at some point in the past, where we created column
sets on the fly during layout, but we don't do that anymore (because we don't
mutate the layout tree structure during layout anymore). If we have no column
sets, it means that we cannot have any lines, since there's no column content
(because if there were, we'd have at least one column set). So it was a
pointless (albeit harmless) check.

There was also a flow thread check around some code that checks if previously
created lines will be affected by floats in new ways. If this is the right
thing to do for flowthread based fragmentation, it's also the right thing to do
for non-flowthread based (e.g. printing) fragmentation, so just remove the
check.

Also reordered and cleaned up checkPaginationAndFloatsAtEndLine() somewhat. We
don't have to do anything at all unless we have floats. Let's figure this out
as early as possible and bail if we can.

Also locate the last line in the block flow in a simpler way. Call
lastRootBox() instead of walking some chain of lines all the way to the end.

Committed: https://crrev.com/ebfc536321dddcab1696da3d87edf9115026be42
Cr-Commit-Position: refs/heads/master@{#389720}

[mstensho (USE GERRIT), 2016-04-25 20:34:50]

mstensho@opera.com changed reviewers:
+ eae@chromium.org, leviw@chromium.org, szager@chromium.org,
wkorman@chromium.org

[leviw_travelin_and_unemployed, 2016-04-25 21:10:36]

The CQ bit was checked by leviw@chromium.org

[leviw_travelin_and_unemployed, 2016-04-25 21:10:37]

lgtm

Awesome simplification!

[commit-bot: I haz the power, 2016-04-25 21:11:05]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1915803004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1915803004/1

[commit-bot: I haz the power, 2016-04-25 22:23:09]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-04-25 22:23:10]

Try jobs failed on following builders:
  linux_chromium_rel_ng on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[mstensho (USE GERRIT), 2016-04-26 06:09:14]

Description was changed from

==========
Remove LayoutFlowThread stuff from line layout code.

We used to force full line layout if we had a flow thread with no column sets.
This may have made sense at some point in the past, where we created column
sets on the fly during layout, but we don't do that anymore (because we don't
mutate the layout tree structure during layout anymore). If we have no column
sets, it means that we cannot have any lines, since there's no column content
(because if there were, we'd have at least one column set). So it was a
pointless (albeit harmless) check.

There was also a flow thread check around some code that checks if previously
created lines will be affected by floats in new ways. If this is the right
thing to do for flowthread based fragmentation, it's also the right thing to do
for non-flowthread based (e.g. printing) fragmentation, so just remove the
check.

Also reordered and cleaned up checkPaginationAndFloatsAtEndLine() somewhat. We
don't have to do anything at all unless we both have floats and are paginated.
Let's figure this out as early as possible and bail if we can.

Also locate the last line in the block flow in a simpler way. Call
lastRootBox() instead of walking some chain of lines all the way to the end.
==========

to

==========
Remove LayoutFlowThread stuff from line layout code.

We used to force full line layout if we had a flow thread with no column sets.
This may have made sense at some point in the past, where we created column
sets on the fly during layout, but we don't do that anymore (because we don't
mutate the layout tree structure during layout anymore). If we have no column
sets, it means that we cannot have any lines, since there's no column content
(because if there were, we'd have at least one column set). So it was a
pointless (albeit harmless) check.

There was also a flow thread check around some code that checks if previously
created lines will be affected by floats in new ways. If this is the right
thing to do for flowthread based fragmentation, it's also the right thing to do
for non-flowthread based (e.g. printing) fragmentation, so just remove the
check.

Also reordered and cleaned up checkPaginationAndFloatsAtEndLine() somewhat. We
don't have to do anything at all unless we have floats. Let's figure this out
as early as possible and bail if we can.

Also locate the last line in the block flow in a simpler way. Call
lastRootBox() instead of walking some chain of lines all the way to the end.
==========

[mstensho (USE GERRIT), 2016-04-26 06:11:00]

Looks like I over-simplified it.

fast/block/float/float-at-start-of-clean-lines-that-are-subsequently-dirtied.html
pointed out to me that we certainly don't need to be paginated for this code to
be useful. But we still need floats, though.

[eae, 2016-04-26 06:12:11]

On 2016/04/26 06:11:00, mstensho wrote:
> Looks like I over-simplified it.
> 
>
fast/block/float/float-at-start-of-clean-lines-that-are-subsequently-dirtied.html
> pointed out to me that we certainly don't need to be paginated for this code
to
> be useful. But we still need floats, though.

Oh floats, always getting in the way....

[mstensho (USE GERRIT), 2016-04-26 06:18:04]

On 2016/04/26 06:12:11, eae wrote:
> Oh floats, always getting in the way....

As defined in the spec. :)

[eae, 2016-04-26 06:21:18]

On 2016/04/26 06:18:04, mstensho wrote:
> On 2016/04/26 06:12:11, eae wrote:
> > Oh floats, always getting in the way....
> 
> As defined in the spec. :)

Well played sir, well played!

[mstensho (USE GERRIT), 2016-04-26 07:36:02]

The CQ bit was checked by mstensho@opera.com

[mstensho (USE GERRIT), 2016-04-26 07:36:02]

The patchset sent to the CQ was uploaded after l-g-t-m from leviw@chromium.org
Link to the patchset: https://codereview.chromium.org/1915803004/#ps20001
(title: "De-awesomeified the patch. We need this when not paginated too, since
lineDelta may be non-zero.")

[commit-bot: I haz the power, 2016-04-26 07:36:17]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1915803004/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1915803004/20001

[commit-bot: I haz the power, 2016-04-26 07:40:08]

Description was changed from

==========
Remove LayoutFlowThread stuff from line layout code.

We used to force full line layout if we had a flow thread with no column sets.
This may have made sense at some point in the past, where we created column
sets on the fly during layout, but we don't do that anymore (because we don't
mutate the layout tree structure during layout anymore). If we have no column
sets, it means that we cannot have any lines, since there's no column content
(because if there were, we'd have at least one column set). So it was a
pointless (albeit harmless) check.

There was also a flow thread check around some code that checks if previously
created lines will be affected by floats in new ways. If this is the right
thing to do for flowthread based fragmentation, it's also the right thing to do
for non-flowthread based (e.g. printing) fragmentation, so just remove the
check.

Also reordered and cleaned up checkPaginationAndFloatsAtEndLine() somewhat. We
don't have to do anything at all unless we have floats. Let's figure this out
as early as possible and bail if we can.

Also locate the last line in the block flow in a simpler way. Call
lastRootBox() instead of walking some chain of lines all the way to the end.
==========

to

==========
Remove LayoutFlowThread stuff from line layout code.

We used to force full line layout if we had a flow thread with no column sets.
This may have made sense at some point in the past, where we created column
sets on the fly during layout, but we don't do that anymore (because we don't
mutate the layout tree structure during layout anymore). If we have no column
sets, it means that we cannot have any lines, since there's no column content
(because if there were, we'd have at least one column set). So it was a
pointless (albeit harmless) check.

There was also a flow thread check around some code that checks if previously
created lines will be affected by floats in new ways. If this is the right
thing to do for flowthread based fragmentation, it's also the right thing to do
for non-flowthread based (e.g. printing) fragmentation, so just remove the
check.

Also reordered and cleaned up checkPaginationAndFloatsAtEndLine() somewhat. We
don't have to do anything at all unless we have floats. Let's figure this out
as early as possible and bail if we can.

Also locate the last line in the block flow in a simpler way. Call
lastRootBox() instead of walking some chain of lines all the way to the end.
==========

[commit-bot: I haz the power, 2016-04-26 07:40:10]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-04-26 07:41:09]

Description was changed from

==========
Remove LayoutFlowThread stuff from line layout code.

We used to force full line layout if we had a flow thread with no column sets.
This may have made sense at some point in the past, where we created column
sets on the fly during layout, but we don't do that anymore (because we don't
mutate the layout tree structure during layout anymore). If we have no column
sets, it means that we cannot have any lines, since there's no column content
(because if there were, we'd have at least one column set). So it was a
pointless (albeit harmless) check.

There was also a flow thread check around some code that checks if previously
created lines will be affected by floats in new ways. If this is the right
thing to do for flowthread based fragmentation, it's also the right thing to do
for non-flowthread based (e.g. printing) fragmentation, so just remove the
check.

Also reordered and cleaned up checkPaginationAndFloatsAtEndLine() somewhat. We
don't have to do anything at all unless we have floats. Let's figure this out
as early as possible and bail if we can.

Also locate the last line in the block flow in a simpler way. Call
lastRootBox() instead of walking some chain of lines all the way to the end.
==========

to

==========
Remove LayoutFlowThread stuff from line layout code.

We used to force full line layout if we had a flow thread with no column sets.
This may have made sense at some point in the past, where we created column
sets on the fly during layout, but we don't do that anymore (because we don't
mutate the layout tree structure during layout anymore). If we have no column
sets, it means that we cannot have any lines, since there's no column content
(because if there were, we'd have at least one column set). So it was a
pointless (albeit harmless) check.

There was also a flow thread check around some code that checks if previously
created lines will be affected by floats in new ways. If this is the right
thing to do for flowthread based fragmentation, it's also the right thing to do
for non-flowthread based (e.g. printing) fragmentation, so just remove the
check.

Also reordered and cleaned up checkPaginationAndFloatsAtEndLine() somewhat. We
don't have to do anything at all unless we have floats. Let's figure this out
as early as possible and bail if we can.

Also locate the last line in the block flow in a simpler way. Call
lastRootBox() instead of walking some chain of lines all the way to the end.

Committed: https://crrev.com/ebfc536321dddcab1696da3d87edf9115026be42
Cr-Commit-Position: refs/heads/master@{#389720}
==========

[commit-bot: I haz the power, 2016-04-26 07:41:11]

Patchset 2 (id:??) landed as
https://crrev.com/ebfc536321dddcab1696da3d87edf9115026be42
Cr-Commit-Position: refs/heads/master@{#389720}