Remove LayoutTable::m_currentBorder

Remove LayoutTable::m_currentBorder

It's merely for TablePainter to tell TableCellPainter which collapsed
border to paint during painting. Now pass it directly through parameter
of TableSectionPainter::paintCollapsedBorders() and
TableCellPainter::paintCollapsedBorders().

Other changes:
- PaintPhaseCollapsedTableBorders no longer needs to be a paint phase;
- Removed the original slow path in TableSectionPainter::paintObject
  for collapsed borders, because collapsed borders are not affected by
  cell overflows, and overlapping cells because of spans also don't
  affect painting order of their collapsed borders;
- When collapsed border changes, invalidate the cell on table because
  collapsed borders are always painted on the table's backing, even if
  any section, row or cell has composited layer.

BUG=510492
Committed: https://crrev.com/cb947c0153db0ec02a8abbcb3ca086d88bf6006f
Cr-Commit-Position: refs/heads/master@{#352221}

[Xianzhu, 2015-10-02 00:58:52]

wangxianzhu@chromium.org changed reviewers:
+ pdr@chromium.org

[Xianzhu, 2015-10-02 18:22:25]

Some notes for reviewer.

https://codereview.chromium.org/1379213002/diff/1/third_party/WebKit/Source/c...
File third_party/WebKit/Source/core/paint/TableSectionPainter.cpp (right):

https://codereview.chromium.org/1379213002/diff/1/third_party/WebKit/Source/c...
third_party/WebKit/Source/core/paint/TableSectionPainter.cpp:61: {
Note: this is extracted from TableSectionPainter::paintObject.

https://codereview.chromium.org/1379213002/diff/1/third_party/WebKit/Source/c...
third_party/WebKit/Source/core/paint/TableSectionPainter.cpp:109: if
(!m_layoutTableSection.hasMultipleCellLevels() && !overflowingCells.size()) {
Note: Actually the amount of change here is much smaller than it looks.
Only changes are:
- Changed the original line 71 'if' to an early return;
- Removed collapsed border code (which is extracted to the new
TableSectionPainter::paintCollapsedBorders()).

The following green lines are just because of change of indent.

[pdr., 2015-10-02 22:05:08]

LGTM. This change looked scary, but ended up being clean.

https://codereview.chromium.org/1379213002/diff/1/third_party/WebKit/Source/c...
File third_party/WebKit/Source/core/layout/LayoutTable.h (right):

https://codereview.chromium.org/1379213002/diff/1/third_party/WebKit/Source/c...
third_party/WebKit/Source/core/layout/LayoutTable.h:383: // TODO(layout-dev):
All mutables in this class (except noted) are lazily updated by recalcSections()
Hmm... what does "except noted" mean?

Can this just be "All mutables in this class are lazily..."?

[Xianzhu, 2015-10-02 22:20:10]

https://codereview.chromium.org/1379213002/diff/1/third_party/WebKit/Source/c...
File third_party/WebKit/Source/core/layout/LayoutTable.h (right):

https://codereview.chromium.org/1379213002/diff/1/third_party/WebKit/Source/c...
third_party/WebKit/Source/core/layout/LayoutTable.h:383: // TODO(layout-dev):
All mutables in this class (except noted) are lazily updated by recalcSections()
On 2015/10/02 22:05:08, pdr wrote:
> Hmm... what does "except noted" mean?
> 
> Can this just be "All mutables in this class are lazily..."?

Done.

(Thought in case we add a mutable for another purpose in the future, we don't
need to update this comment.)

[Xianzhu, 2015-10-02 22:20:15]

The CQ bit was checked by wangxianzhu@chromium.org

[Xianzhu, 2015-10-02 22:20:15]

The patchset sent to the CQ was uploaded after l-g-t-m from pdr@chromium.org
Link to the patchset: https://codereview.chromium.org/1379213002/#ps20001
(title: "Update comment")

[commit-bot: I haz the power, 2015-10-02 22:21:04]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1379213002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1379213002/20001

[commit-bot: I haz the power, 2015-10-03 01:33:41]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-10-03 01:34:56]

Patchset 2 (id:??) landed as
https://crrev.com/cb947c0153db0ec02a8abbcb3ca086d88bf6006f
Cr-Commit-Position: refs/heads/master@{#352221}