[DO NOT COMMIT] Don't keep pointers to table sections when told to recalculate sections.

[DO NOT COMMIT] Don't keep pointers to table sections when told to recalculate sections.

Experiments to investigate the problems with landing https://codereview.chromium.org/2636153002/

Additions, compared to that CL:

DCHECK in various mapToVisualRectInAncestorSpace() implementations that we're laid out.

[mstensho (USE GERRIT), 2017-01-18 13:10:10]

Description was changed from

==========
[DO NOT COMMIT] Don't keep pointers to table sections when told to recalculate
sections.

They may have been deleted.

Assert in header(), footer() and firstBody() in LayoutTable that we're not
waiting for a section recalc.

This fixes the use-after-free issue with bug 680224, but now we get a (albeit
way more harmless) assertion failure instead.

BUG=680224

patch from issue 2636153002 at patchset 1 (http://crrev.com/2636153002#ps1)

DCHECK in various mapToVisualRectInAncestorSpace() implementations that we're
laid out.
==========

to

==========
[DO NOT COMMIT] Don't keep pointers to table sections when told to recalculate
sections.

They may have been deleted.

Assert in header(), footer() and firstBody() in LayoutTable that we're not
waiting for a section recalc.

This fixes the use-after-free issue with bug 680224, but now we get a (albeit
way more harmless) assertion failure instead.

BUG=680224

patch from issue 2636153002 at patchset 1 (http://crrev.com/2636153002#ps1)

DCHECK in various mapToVisualRectInAncestorSpace() implementations that we're
laid out.
==========

[mstensho (USE GERRIT), 2017-01-18 19:39:14]

Description was changed from

==========
[DO NOT COMMIT] Don't keep pointers to table sections when told to recalculate
sections.

They may have been deleted.

Assert in header(), footer() and firstBody() in LayoutTable that we're not
waiting for a section recalc.

This fixes the use-after-free issue with bug 680224, but now we get a (albeit
way more harmless) assertion failure instead.

BUG=680224

patch from issue 2636153002 at patchset 1 (http://crrev.com/2636153002#ps1)

DCHECK in various mapToVisualRectInAncestorSpace() implementations that we're
laid out.
==========

to

==========
[DO NOT COMMIT] Don't keep pointers to table sections when told to recalculate
sections.

Experiments to investigate the problems with landing
https://codereview.chromium.org/2636153002/

Additions, compared to that CL:

DCHECK in various mapToVisualRectInAncestorSpace() implementations that we're
laid out.
==========