Remove an extra relayout for non-percent logical height grid items

Remove an extra relayout for non-percent logical height grid items

The only reason for a grid item to force a relayout after a grid
area's logical height change is if it has a percentage height. In
all other cases, this would cause an unneeded relayout. Note that
changing the logical width still forces a relayout as the situation
is not that simple.

This improves auto-grid-lots-of-data.html from 94 runs/s to 226
runs/s as we avoid a relayout in layoutGridItems for every grid
items.

BUG=273238
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=157633

[eseidel, 2013-09-06 22:21:04]

I'm sure ojan is a better reviewer for grid than I am, but lgtm.

[ojan, 2013-09-07 17:13:20]

https://codereview.chromium.org/23694023/diff/1/Source/core/rendering/RenderG...
File Source/core/rendering/RenderGrid.cpp (right):

https://codereview.chromium.org/23694023/diff/1/Source/core/rendering/RenderG...
Source/core/rendering/RenderGrid.cpp:853: return logicalHeight.isPercent();
Don't you also need to check maxHeight/minHeight? What about viewport
percentages? You could maybe use RenderBox::hasRelativeLogicalHeight here?

[Julien - ping for review, 2013-09-09 18:04:42]

https://codereview.chromium.org/23694023/diff/1/Source/core/rendering/RenderG...
File Source/core/rendering/RenderGrid.cpp (right):

https://codereview.chromium.org/23694023/diff/1/Source/core/rendering/RenderG...
Source/core/rendering/RenderGrid.cpp:853: return logicalHeight.isPercent();
On 2013/09/07 17:13:20, ojan wrote:
> Don't you also need to check maxHeight/minHeight?

I think you are right, I will add more testing for that.

> What about viewport
> percentages? You could maybe use RenderBox::hasRelativeLogicalHeight here?

AFAICT we are not impacted by viewport percentages.
gridItemDependsOnGridAreaLogicalHeight determines if the grid item's logical
height depends on the grid area's logical height, which is not the case for
viewport percentage.

[Julien - ping for review, 2013-09-11 00:06:05]

https://codereview.chromium.org/23694023/diff/10001/Source/core/rendering/Ren...
File Source/core/rendering/RenderGrid.cpp (right):

https://codereview.chromium.org/23694023/diff/10001/Source/core/rendering/Ren...
Source/core/rendering/RenderGrid.cpp:873: if
(oldOverrideContainingBlockContentLogicalWidth !=
overrideContainingBlockContentLogicalWidth || (child->hasRelativeLogicalHeight()
&& oldOverrideContainingBlockContentLogicalHeight !=
overrideContainingBlockContentLogicalHeight))
I went ahead and switched to RenderBox::hasRelativeLogicalHeight. Ojan, WDYT?

[ojan, 2013-09-11 21:52:02]

lgtm

[commit-bot: I haz the power, 2013-09-11 22:03:50]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/jchaffraix@chromium.org/23694023/10001

[commit-bot: I haz the power, 2013-09-11 23:26:08]

Change committed as 157633