CSS 2.2 section 9.5.1:
The outer top of a floating box may not be higher than the
outer top of any _block_ or floated box generated by an
element earlier in the source document.
Where block is `BlockContainer` in LibWeb type system.
Which means `current_boxes` need to be cleared before
leaving block container.
```html
<style>
.wrapper {
width: 100px;
height: 300px;
background-color: lightgray;
}
.box {
margin: 10px;
width: 50px;
height: 50px;
float: left;
}
.a { background-color: salmon; }
.b { background-color: slateblue; }
.c { background-color: green; }
</style>
<div class="wrapper">
<div class="box a"></div>
<div class="box b"></div>
</div>
<div class="box c">
</div>
```
Introduce `TableWrapper` type so table wrappers could be
distinguished from block containers and override width
calculation for table wrappers (CSS 2.2 spec, section 17.5.2)
inside BFCs in the way that their width should be equal to
width of table box they wrap.
Before this patch, we were expressing the current selection as a range
between two points in the layout tree. This was a made-up concept I
called LayoutRange (2x LayoutPosition) and as it turns out, we don't
actually need it!
Instead, we can just use the Selection API from the Selection API spec.
This API expresses selection in terms of the DOM, and we already had
many of the building blocks implemented.
To ensure that selections get visually updated when the underlying Range
of an active Selection is programmatically manipulated, Range now has
an "associated Selection". If a range is updated while associated with
a selection, we recompute layout tree selection states and repaint the
page to make it user-visible.
This simplifies the ownership model between DOM/layout/paint nodes
immensely by deferring to the garbage collector for figuring out what's
live and what's not.
This change fixes problem that y position of blocks with
clearance might not include border_top and padding_top
by changing `place_block_level_element_in_normal_flow_vertically`
to accept y position without `border_box_top` and adding it
on the last step when clearance is already taken in account.
Bug reproducer:
```html
<style>
.a {
border: 10px salmon solid;
width: 50px;
height: 50px;
float: left;
}
.b {
clear: both;
border: 20px slateblue solid;
width: 50px;
height: 50px;
}
</style>
<div class="a"></div><div class="b"></div><div class="c"></div>
```
Introduce `table_box()` function that returns table formatting
context root box casted to `TableBox` similar to how it's done
in other formatting contexts like `root()` in BFC and
`flex_container` in FFC. And replace `context_box()` calls
in TFC with calls to `table_box()`.
It is incorrect to skip anonymous block containers without
line boxes during block auto height calculation because there
might be table roots wrapped in anonymous table boxes after fixup
and their height should be taken in account so leaving just
condition to skip child boxes which margins are "collapsed
through" (`border_box_height() == 0`) sufficient to skip
anonymous blocks without lines but still consider table wrappers.
According to table fixup algorithm:
https://www.w3.org/TR/css-tables-3/#fixup-algorithm
around every table-root should be generated anonymous
box wrapper.
Also this patch implements important part of CSS 2.2
spec that is currently not present in CSS Tables 3
spec draft: https://www.w3.org/TR/CSS22/tables.html#model
that portion of computed properties should be moved
from table-root to table wrapper box. Without having
this part implemented height of absolutely positioned
table with `height: auto` won't be computed correctly.
Fixup rule that table roots need to be wrapped in anonymous
block boxes need to be implemeted instead of having `TableBox`
inherited from `BlockContainer`.
When calculating intrinsic heights of flex items, we should use the used
width if available.
This primarily matters for item cross sizing, since that happens after
we've determined the item's main size.
We were trying to take a shortcut by avoiding much of the flex layout
algorithm during intrinsic sizing. Unfortunately, this isn't good enough
since we may end up needing some of the flex item metrics for intrinsic
contribution calculations.
This means we do a bit more work for flexboxes, but intrinsic sizes are
correct in more cases.
When laying out abspos boxes, we compute the height twice: before and
after the inside of the box has been laid out.
The first pass allows percentage vertical values inside the box to be
resolved against the box's height. The second pass resolves the final
used value for the height of the box itself.
In cases where the box height depends on the results of inside layout,
we were incorrectly setting the box to having a definite zero height.
This led to incorrect results when sizing an abspos flex container,
since the FFC sizes containers (in row layouts) based on whether the
container has a definite height.
To avoid this problem, this patch adds an enum so we can differentiate
between the two abspos height computation passes. If the first pass
discovers a dependency on the inside layout, we simply bail out of
computing the height, leaving it as indefinite. This allows the FFC
to size its container correctly, and the correct height gets set by
the second pass.
Change column distribution to take in account is_length() and
is_percentage() width values instead of treating all cells like
they have auto width by implementing it in the way described
in CSS Tables 3 spec:
https://www.w3.org/TR/css-tables-3/#width-distribution-algorithm
distribute_width_to_column() is structured to follow schema:
w3.org/TR/css-tables-3/images/CSS-Tables-Column-Width-Assignment.svg
It is not possible to use width of containing block to resolve
cells width because by the time compute_table_measures() is
called row width is not known yet.
