Remove obsolete float-management code from line layout

Remove obsolete float-management code from line layout

This code was added in http://wkbug.com/33245 and http://wkbug.com/19278.

Second go at removing this, with some test cases by mstensho the previous attempt flushed out
added to the CL. One of the tests highlighted the need to watch for a trailing
float that can occur after a soft line break and dirty its lineboxes so that it
can get placed.

BUG=487775
Committed: https://crrev.com/f21b66a8a4f722e18ed43daee02c703f178eabd7
git-svn-id: svn://svn.chromium.org/blink/trunk@199616 bbb929c8-8fbe-4397-9dbb-9b2b20218538

[rhogan, 2015-05-13 21:02:47]

robhogan@gmail.com changed reviewers:
+ leviw@chromium.org

[leviw_travelin_and_unemployed, 2015-05-18 22:29:25]

I think I just shed a tear for the float code. This is fantastic!

LGTM++!

[leviw_travelin_and_unemployed, 2015-05-18 22:29:28]

The CQ bit was checked by leviw@chromium.org

[commit-bot: I haz the power, 2015-05-18 22:29:38]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1132103007/1

[commit-bot: I haz the power, 2015-05-19 00:17:42]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=195493

[rhogan, 2015-07-23 10:21:41]

On 2015/05/19 at 00:17:42, commit-bot wrote:
> Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=195493

I'm having another go at this - with some test cases added from the previous
attempt. Can you take a look leviw?

[leviw_travelin_and_unemployed, 2015-07-28 18:25:38]

https://codereview.chromium.org/1132103007/diff/40001/Source/core/layout/Layo...
File Source/core/layout/LayoutBlockFlowLine.cpp (right):

https://codereview.chromium.org/1132103007/diff/40001/Source/core/layout/Layo...
Source/core/layout/LayoutBlockFlowLine.cpp:1570: // then dirty its adjacent
lineboxes to ensure it gets placed.
If it's the last child and a float, will we ever be dirtying more than one
linebox?

https://codereview.chromium.org/1132103007/diff/40001/Source/core/layout/Layo...
Source/core/layout/LayoutBlockFlowLine.cpp:1572:
dirtyLinesFromChangedChild(lastChild);
Where did we dirty these lines before?

[rhogan, 2015-07-28 19:10:37]

https://codereview.chromium.org/1132103007/diff/40001/Source/core/layout/Layo...
File Source/core/layout/LayoutBlockFlowLine.cpp (right):

https://codereview.chromium.org/1132103007/diff/40001/Source/core/layout/Layo...
Source/core/layout/LayoutBlockFlowLine.cpp:1570: // then dirty its adjacent
lineboxes to ensure it gets placed.
On 2015/07/28 at 18:25:38, leviw wrote:
> If it's the last child and a float, will we ever be dirtying more than one
linebox?

The one it's on and possibly the one before it. There would be no line boxes
after it obviously.

https://codereview.chromium.org/1132103007/diff/40001/Source/core/layout/Layo...
Source/core/layout/LayoutBlockFlowLine.cpp:1572:
dirtyLinesFromChangedChild(lastChild);
On 2015/07/28 at 18:25:38, leviw wrote:
> Where did we dirty these lines before?

We didn't. Instead we added a new line box at the end of the block and placed
the float there, even though it wasn't a 'new' one. This allowed us to overwrite
the 'originatingLine' that the float uses to track the linebox it sits in. It
also left an unnecessary linebox sitting around before it.

My change, instead of relying on this layoutState.checkForFloatsFromLastLine()
check, instead gets rid of the linebox the float is attached to so that
positionNewFloats() returns true, i.e. we're placing a new float and have to
find a linebox for it. That allows us to add it to its linebox in
appendFloatingObjectToLastLine() in the new line 1032 above and overwrite the
'originatingLine' it stores.

I think this also leaves us with fewer unnecessary lineboxes in this scenario.
(The test case is trailing-float.html)

[leviw_travelin_and_unemployed, 2015-07-28 23:19:42]

The CQ bit was checked by leviw@chromium.org

[leviw_travelin_and_unemployed, 2015-07-28 23:19:42]

lgtm

This seems reasonable.

[commit-bot: I haz the power, 2015-07-28 23:19:54]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1132103007/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1132103007/40001

[commit-bot: I haz the power, 2015-07-29 00:30:53]

Committed patchset #3 (id:40001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=199616

[commit-bot: I haz the power, 2015-09-23 11:52:03]

Patchset 3 (id:??) landed as
https://crrev.com/f21b66a8a4f722e18ed43daee02c703f178eabd7