Iterate Through Fewer Children When Seeking Overhanging Floats

Iterate Through Fewer Children When Seeking Overhanging Floats

If a container's height is reduced it doesn't need to iterate through all
its children looking for floats that might now overhang - it only needs to
look back through float-containing children and even then only as far as the last
child with a float in its list of own/intruding floats that overhangs
the container's new height.

We also don't need to track the bottom position of the lowest hanging float
we encounter; we get that for free when we look at the lowestFloatLogicalBottom()
of the last child. This is so because each child keeps a copy of any
floats intruding from the previous sibling in its float list.

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=171906

[leviw_travelin_and_unemployed, 2014-04-15 20:27:29]

LGTM. Just to be clear: the test cases you added still passed prior to this
patch, correct?

https://codereview.chromium.org/228663014/diff/60001/Source/core/rendering/Re...
File Source/core/rendering/RenderBlockFlow.cpp (right):

https://codereview.chromium.org/228663014/diff/60001/Source/core/rendering/Re...
Source/core/rendering/RenderBlockFlow.cpp:630: if (childRenderBlockFlow)
You're taking out the check because we already check in addOverhangingFloats?

[rhogan, 2014-04-15 20:33:04]

On 2014/04/15 20:27:29, Levi wrote:
> LGTM. Just to be clear: the test cases you added still passed prior to this
> patch, correct?
> 
Correct, they don't exist at the moment. I added them to protect the next guy
from briefly dreaming that we only needed to inspect the last child for
overhanging floats.

>
https://codereview.chromium.org/228663014/diff/60001/Source/core/rendering/Re...
> File Source/core/rendering/RenderBlockFlow.cpp (right):
> 
>
https://codereview.chromium.org/228663014/diff/60001/Source/core/rendering/Re...
> Source/core/rendering/RenderBlockFlow.cpp:630: if (childRenderBlockFlow)
> You're taking out the check because we already check in addOverhangingFloats?

Yes, there's an early return in there.

[rhogan, 2014-04-17 17:46:48]

The CQ bit was checked by robhogan@gmail.com

[commit-bot: I haz the power, 2014-04-17 17:47:08]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/robhogan@gmail.com/228663014/60001

[commit-bot: I haz the power, 2014-04-17 19:05:44]

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

[commit-bot: I haz the power, 2014-04-17 19:05:44]

Try jobs failed on following builders:
  tryserver.blink on linux_blink_dbg

[rhogan, 2014-04-17 22:46:11]

The CQ bit was checked by robhogan@gmail.com

[commit-bot: I haz the power, 2014-04-17 22:46:46]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/robhogan@gmail.com/228663014/60001

[commit-bot: I haz the power, 2014-04-17 23:55:49]

Change committed as 171906