Adjust column rows' height better for their offset in the multicol container.

Adjust column rows' height better for their offset in the multicol container.

We were missing the case where the first object in a multicol container was a
spanner (the call to previousSiblingMultiColumnSet() should have been
previousSiblingMultiColumnBox(), to catch spanner placeholders in addition to
column sets).

But instead of having a special code path depending on whether we're dealing
with the first box or not (to avoid subtracting the multicol container's top
border and padding from an uncalculated logical top of a column set), always
subtract the margin top edge of the first column box instead.

R=leviw@chromium.org

Committed: https://crrev.com/86d53e7bdc322fb562163695c0f37ac671977a4b
Cr-Commit-Position: refs/heads/master@{#371661}

[mstensho (USE GERRIT), 2016-01-25 18:07:48]

Hm.. I was just going to clean up this code, but then I found a bug.

[leviw_travelin_and_unemployed, 2016-01-26 23:00:29]

The CQ bit was checked by leviw@chromium.org

[leviw_travelin_and_unemployed, 2016-01-26 23:00:30]

lgtm

Sorry I missed this the first time around.

https://codereview.chromium.org/1631633002/diff/1/third_party/WebKit/Source/c...
File third_party/WebKit/Source/core/layout/MultiColumnFragmentainerGroup.cpp
(right):

https://codereview.chromium.org/1631633002/diff/1/third_party/WebKit/Source/c...
third_party/WebKit/Source/core/layout/MultiColumnFragmentainerGroup.cpp:295: //
Let's avoid zero height, as that would cause an infinite amount of columns to be
created.
Where's the fun in that?

If we can just sell the columns for $0.01 we'll be RICH! Think of all the spam,
sausage, lobster, egg, bread, and beer we could buy!

[commit-bot: I haz the power, 2016-01-26 23:04:14]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1631633002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1631633002/1

[commit-bot: I haz the power, 2016-01-27 00:38:27]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-01-27 00:39:52]

Description was changed from

==========
Adjust column rows' height better for their offset in the multicol container.

We were missing the case where the first object in a multicol container was a
spanner (the call to previousSiblingMultiColumnSet() should have been
previousSiblingMultiColumnBox(), to catch spanner placeholders in addition to
column sets).

But instead of having a special code path depending on whether we're dealing
with the first box or not (to avoid subtracting the multicol container's top
border and padding from an uncalculated logical top of a column set), always
subtract the margin top edge of the first column box instead.

R=leviw@chromium.org
==========

to

==========
Adjust column rows' height better for their offset in the multicol container.

We were missing the case where the first object in a multicol container was a
spanner (the call to previousSiblingMultiColumnSet() should have been
previousSiblingMultiColumnBox(), to catch spanner placeholders in addition to
column sets).

But instead of having a special code path depending on whether we're dealing
with the first box or not (to avoid subtracting the multicol container's top
border and padding from an uncalculated logical top of a column set), always
subtract the margin top edge of the first column box instead.

R=leviw@chromium.org

Committed: https://crrev.com/86d53e7bdc322fb562163695c0f37ac671977a4b
Cr-Commit-Position: refs/heads/master@{#371661}
==========

[commit-bot: I haz the power, 2016-01-27 00:39:53]

Patchset 1 (id:??) landed as
https://crrev.com/86d53e7bdc322fb562163695c0f37ac671977a4b
Cr-Commit-Position: refs/heads/master@{#371661}

[mstensho (USE GERRIT), 2016-01-27 09:51:45]

https://codereview.chromium.org/1631633002/diff/1/third_party/WebKit/Source/c...
File third_party/WebKit/Source/core/layout/MultiColumnFragmentainerGroup.cpp
(right):

https://codereview.chromium.org/1631633002/diff/1/third_party/WebKit/Source/c...
third_party/WebKit/Source/core/layout/MultiColumnFragmentainerGroup.cpp:295: //
Let's avoid zero height, as that would cause an infinite amount of columns to be
created.
On 2016/01/26 23:00:29, leviw wrote:
> Where's the fun in that?
> 
> If we can just sell the columns for $0.01 we'll be RICH! Think of all the
spam,
> sausage, lobster, egg, bread, and beer we could buy!

I can do that in a follow-up patch. You're right. This can be monetized! Surely
there's a market for all the super-short columns that we don't need.