The concept of inherited style is about to get a bit more complicated, and this
will prevent consumers from doing it wrong.
Part 1 of Gecko bug1382806. r=emilio
While decomposing a 3D matrix, we should normalize the 2nd row right after the
Y scale computation. However, we accidentally use the length of the 1st row to
do the normalization. This causes the wrong Scale3D function while decomposing,
and then leads to the wrong decomposed 3D matrix.
Here, we correct it by using the right value (the length of the 2nd row).
r=hiro https://bugzilla.mozilla.org/show_bug.cgi?id=1381196
Store font-weight as integer directly
It doesn't make much sense to store `font-weight` as separate enums, especially given that we would need to support (somehow) arbitrary font weight value when we implement CSS Fonts Level 4.
This PR refactors the `font-weight` a bit to make it store as `u16` directly.
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We have to build an identity matrix while add_weighted() between
InterpolateMatrix and none transform in some cases, e.g. trigger a
transition from a mid-point of another transition to none.
If the units of two angles being interpolated/added matches, we should preserve
the original unit; otherwise, we fall back to radians. This matches the behavior
of Gecko.
Now we have AnimatableLonghand (to do with animatability) and
TransitionProperty (to do with transitionability), we should move
nscssproperty_id_is_animatable to be part of the former group.
Currently properties that are discretely animated cannot be
transitioned. Now that TransitionProperty should only be used for
transitions, we can redefine it to treat non-transitionable properties
as unsupported. This should allow us to simplify the code and make it
more self-documenting (e.g. making TransitionProperty actually relate to
transitions).
In the next few patches we move all non-transition related code over to
using AnimatableLonghand instead of TransitionProperty. This will allow
us to re-purpose TransitionProperty to represent only properties that
can be transitioned (i.e. excluding discrete properties) as well as
simplifying the code by removing the need to deal with shorthands and
the "all" value in places that do not need to handle those values.
This type, which we will use in the next patch in this series, can
represent only longhands whose animation type is not "none". By
introducing this type, we can later restrict the meaning of
TransitionProperty to only cover properties whose animation type is not
"none" OR "discrete" (since currently CSS transitions should not animate
properties whose animation type is discrete). Doing so will also mean
that CSS transitions ignore the 'display' property by default.
Furthermore, introducing this type will allow the animation code to
clearly document when a property is allowed to be a shorthand or
unanimatable property and when it is expected to be an animatable
longhand. This, in turn, will allow us to remove a few
no-longer-necessary checks and simplify the code.
