Fix order of operations in LayoutView::mapAncestorToLocal

Fix order of operations in LayoutView::mapAncestorToLocal

mapAncestorToLocal should first recurse, then apply each of the offsets/transforms
in the forward direction but inverse order.

The forward direction will be transformed to backwards direction by the TransformState state bit indicating "unapply inverse direction".
This was incorrectly fixed in https://codereview.chromium.org/1994203003.

Also, remove code to handle transforms on the LayoutView. It's impossible
to have such a transform from content. This code was added in:

https://chromium.googlesource.com/chromium/src/+/ce75f4f9824faae4464420cf9c96a6cf0fb85c77

without comment as to why.

BUG=613894
Committed: https://crrev.com/d74f43ae4a3e5cc9392c15728be21e3f2d14a1be
Cr-Commit-Position: refs/heads/master@{#408434}

[chrishtr, 2016-07-11 18:45:50]

Description was changed from

==========
none

BUG=
==========

to

==========
Fix order of operations in LayoutView::mapAncestorToLocal

mapAncestorToLocal should first recurse, then apply each of the
offsets/transforms
in the forward direction but inverse order.

The forward direction will be transformed to backwards direction by the
TransformState state bit indicating "unapply inverse direction".

BUG=613894
==========

[chrishtr, 2016-07-13 16:13:22]

Description was changed from

==========
Fix order of operations in LayoutView::mapAncestorToLocal

mapAncestorToLocal should first recurse, then apply each of the
offsets/transforms
in the forward direction but inverse order.

The forward direction will be transformed to backwards direction by the
TransformState state bit indicating "unapply inverse direction".

BUG=613894
==========

to

==========
Fix order of operations in LayoutView::mapAncestorToLocal

mapAncestorToLocal should first recurse, then apply each of the
offsets/transforms
in the forward direction but inverse order.

The forward direction will be transformed to backwards direction by the
TransformState state bit indicating "unapply inverse direction".
This was incorrectly fixed in https://codereview.chromium.org/1994203003.

Also, remove code to handle transforms on the LayoutView. It's impossible
to have such a transform from content. This code was added in:

https://chromium.googlesource.com/chromium/src/+/ce75f4f9824faae4464420cf9c96...

without comment as to why.

BUG=613894
==========

[chrishtr, 2016-07-14 17:29:10]

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

[chrishtr, 2016-07-14 17:29:11]

Please check my logic closely. I got it wrong last time. :(

[Xianzhu, 2016-07-14 17:40:12]

Can you add a test case?

https://codereview.chromium.org/2141693002/diff/60001/third_party/WebKit/Sour...
File third_party/WebKit/Source/core/layout/LayoutView.cpp (right):

https://codereview.chromium.org/2141693002/diff/60001/third_party/WebKit/Sour...
third_party/WebKit/Source/core/layout/LayoutView.cpp:382: // A LayoutView is a
containing block for fixed-position elements, so don't carry this state across
frames.
Move this comment to above line 380.

https://codereview.chromium.org/2141693002/diff/60001/third_party/WebKit/Sour...
third_party/WebKit/Source/core/layout/LayoutView.cpp:384:
transformState.move(-frame()->view()->scrollOffset());
Can this be:
   if (!(mode & IsFixed))
      transformState.move(-frame()->view()->scrollOffset());
   return;
to avoid moving back and forth for fixed?

[chrishtr, 2016-07-28 16:21:13]

Test added. This test fails without the change to LayoutView.

https://codereview.chromium.org/2141693002/diff/60001/third_party/WebKit/Sour...
File third_party/WebKit/Source/core/layout/LayoutView.cpp (right):

https://codereview.chromium.org/2141693002/diff/60001/third_party/WebKit/Sour...
third_party/WebKit/Source/core/layout/LayoutView.cpp:382: // A LayoutView is a
containing block for fixed-position elements, so don't carry this state across
frames.
On 2016/07/14 at 17:40:11, Xianzhu wrote:
> Move this comment to above line 380.

Done.

https://codereview.chromium.org/2141693002/diff/60001/third_party/WebKit/Sour...
third_party/WebKit/Source/core/layout/LayoutView.cpp:384:
transformState.move(-frame()->view()->scrollOffset());
On 2016/07/14 17:40:11, Xianzhu wrote:
> Can this be:
>    if (!(mode & IsFixed))
>       transformState.move(-frame()->view()->scrollOffset());
>    return;
> to avoid moving back and forth for fixed?

I could, but then I would have to add an else clause if
TraverseDocumentBoundaries was false.

[Xianzhu, 2016-07-28 16:29:12]

lgtm

[Xianzhu, 2016-07-28 16:29:21]

The CQ bit was checked by wangxianzhu@chromium.org

[commit-bot: I haz the power, 2016-07-28 16:29:45]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[chrishtr, 2016-07-28 16:38:15]

The CQ bit was unchecked by chrishtr@chromium.org

[chrishtr, 2016-07-28 16:46:10]

The CQ bit was checked by chrishtr@chromium.org

[commit-bot: I haz the power, 2016-07-28 16:46:28]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-07-28 18:03:46]

Committed patchset #5 (id:80001)

[commit-bot: I haz the power, 2016-07-28 18:06:21]

Description was changed from

==========
Fix order of operations in LayoutView::mapAncestorToLocal

mapAncestorToLocal should first recurse, then apply each of the
offsets/transforms
in the forward direction but inverse order.

The forward direction will be transformed to backwards direction by the
TransformState state bit indicating "unapply inverse direction".
This was incorrectly fixed in https://codereview.chromium.org/1994203003.

Also, remove code to handle transforms on the LayoutView. It's impossible
to have such a transform from content. This code was added in:

https://chromium.googlesource.com/chromium/src/+/ce75f4f9824faae4464420cf9c96...

without comment as to why.

BUG=613894
==========

to

==========
Fix order of operations in LayoutView::mapAncestorToLocal

mapAncestorToLocal should first recurse, then apply each of the
offsets/transforms
in the forward direction but inverse order.

The forward direction will be transformed to backwards direction by the
TransformState state bit indicating "unapply inverse direction".
This was incorrectly fixed in https://codereview.chromium.org/1994203003.

Also, remove code to handle transforms on the LayoutView. It's impossible
to have such a transform from content. This code was added in:

https://chromium.googlesource.com/chromium/src/+/ce75f4f9824faae4464420cf9c96...

without comment as to why.

BUG=613894

Committed: https://crrev.com/d74f43ae4a3e5cc9392c15728be21e3f2d14a1be
Cr-Commit-Position: refs/heads/master@{#408434}
==========

[commit-bot: I haz the power, 2016-07-28 18:06:22]

Patchset 5 (id:??) landed as
https://crrev.com/d74f43ae4a3e5cc9392c15728be21e3f2d14a1be
Cr-Commit-Position: refs/heads/master@{#408434}