Previously we would only update these if:
a) We had a cascaded value for `transition-property`
b) The source of that cascaded value had changed since we last
registered transitions
This meant that there were a lot of changes we didn't apply:
- Changes exclusively to properties other than `transition-property`
(e.g. `transition-duration`, `transition-behavior`, etc)
- Removing the `transition-property` property
- Updating the `transition-property` property in a way that didn't
change it's source (e.g. setting it within inline-style)
Unfortunately this does mean that we now register transitions for all
properties on most elements since "all" is the initial value for
"transition-property" which isn't great for performance, but that can be
looked at in later commits.
In several content calculation methods in FormattingContext, we assumed
that if create_independent_formatting_context_if_needed() fails the
input Layout::Box is a BlockContainer; however, the web platform test
css/css-pseudo/parsing/marker-supported-properties-in-animation.html is
one scenario where the input is a Layout::ListItemMarkerBox instead and
there is no FormattingContext supported for it yet.
