This replaces before_remove_attr(), after_remove_attr() and after_set_attr().
The virtual method takes the mutated attribute and an AttributeMutation value
to disambiguate between "attribute is changed", "attribute is added" and
"attribute is removed".
In the case of "attribute is changed", the mutation value contains a reference
to the old value of the mutated attribute, which is used to unregister outdated
named elements when the "id" attribute is changed on an element.
This greatly simplifies the handling of attributes, which in many cases don't
have any specific behaviour whether they are removed or changed or added. It
also fixes a few bugs where things were put in before_remove_attr() instead of
after_remove_attr() (e.g. when removing an href attribute from a base element).
A few helper functions in Element were also renamed and made private.
Extracted this out of #5649
This commit was created with the following commands:
```
find . -iname "*.webidl" -type f -print0 | xargs -0 sed -i '' 's/http:\(.*\)whatwg.org/https:\1whatwg.org/g'
```
```
find . -iname "*.rs" -type f -print0 | xargs -0 sed -i '' 's/http:\(.*\)whatwg.org/https:\1whatwg.org/g'
```
`cellspacing` attribute per HTML5 § 14.3.9.
Table layout code has been refactored to push the spacing down to
rowgroups and rows; this will aid the implementation of
`border-collapse` as well.
This commit also fixes two nasty issues in table layout:
* In fixed layout, extra space would not be divided among columns that
had auto width but had nonzero minimum width.
* In automatic layout, extra space would be distributed to constrained
columns as well even if unconstrained columns with percentage equal to
zero were present.
This used to conflict with the util crate from the standard library, which
has long since been removed.
The import in layout has not been changed because of a conflict with the
util mod there.
This patch provides some of the groundwork for column spans greater than
1. It implements the column-span CSS property (prefixed so as not to be
exposed to content) as well as the corresponding colspan attribute;
although the former is not well-specified outside of CSS multi-column
layout, INTRINSIC refers to it. Although width is distributed to
spanning columns, they do not yet contribute minimum and preferred
widths; this will be implemented in a follow-up.
Additionally, this patch cleans up some miscellaneous formatting issues
and improves the handling of table rowgroups.
Additionally, this patch cleans up some miscellaneous formatting issues
and refactors files in `layout/css/` somewhat to eliminate needless
levels of indirection. It also fixes our handling of presentational
hints that only apply if border is nonzero.
Replace &JSRef with JSRef in the bulk of the generated code. This will
remove a level of indirection throughout all DOM code.
This patch doesn't change methods implemented on JSRef<T> to take `self`
rather than `&self`, and it leaves a few other uses of &JSRef, but those
changes can be made incrementally.
