I'm about to introduce more state here to implement optimizations for custom
property cascading, so this abstraction is useful to encapsulate that state.
In custom_properties::SpecifiedValue::parse.
It's not a big deal now, but it's useful to simplify testing this stuff, since
it avoids forcing us to mock it.
In #18745, I replaced a few manual iterations over `index` with the iterator,
and it changed the behavior of `layout/style/test/test_variables_order.html`,
since it turns out that the iterator iterates right to left.
I think this is just an accident that happened due to inconsistencies in how we
were iterating over it, and that our behavior was inconsistent (since we
iterated rtl in some cases, but ltr in others seems like it'd be inconsistent
depending on the depth of the tree and different stuff).
This brings back the expected behavior again, and ensures we iterate over a
consistent order every time.
This patch replaces the handwritten MallocSizeOf implementation for
PropertyDeclaration with a derived one, which gives much more thorough
measurement.
This requires (a) deriving MallocSizeOf for a *lot* of additional types (most
of which already have `derive(HeapSizeOf)` in Servo builds), and (b)
implementing MallocSizeOf for a few more types in the `malloc_size_of` crate.
These changes would significantly improve the reporting coverage for gmail if
it weren't for the fact that SpecifiedUrl isn't measured due to a lack of
clarity about its fields; that can be fixed as a follow-up once bug 1397971 has
landed.
The alias is left there temporarilly and will be removed completely in a later commit where
also components/style/gecko/generated/structs_{debug|release}.rs are re-generated (they still
use the old alias).
Propagate changes in custom properties' computed values to descendants
If ComputedValues.custom_properties differs between the old and new
ComputedValues, indicate that we have to propogate changes to
descendants by setting child_cascade_requirement to
MustCascadeDescendants in cascade_primary.
style::matching::TElement::cascade_primary already calls
accumulate_damage, which eventually calls
ServoRestyleDamage::compute_style_difference in order to check if other
properties' computed values changed. If any of those change, we signal
that we need to propogate changes for inherited properties.
With Properties & Values, some custom properties will not be inherited,
and we will need to revisit this.
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If ComputedValues.custom_properties differs between the old and new
ComputedValues, indicate that we have to propogate changes to
descendants by setting child_cascade_requirement to
MustCascadeDescendants in cascade_primary.
style::matching::TElement::cascade_primary already calls
accumulate_damage, which eventually calls
ServoRestyleDamage::compute_style_difference in order to check if other
properties' computed values changed. If any of those change, we signal
that we need to propogate changes for inherited properties.
With Properties & Values, some custom properties will not be inherited,
and we will need to revisit this.
From https://bugzilla.mozilla.org/show_bug.cgi?id=1347719
This effectively combines the discriminants of the two enums and reduces the
size of PropertyDeclaration by one word.
MozReview-Commit-ID: 9rCRiSVZTQT
