Prefixed intrinsic size value
<!-- Please describe your changes on the following line: -->
This is a PR for https://bugzilla.mozilla.org/show_bug.cgi?id=1355402
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix#16788
- [X] These changes do not require tests because it's for stylo
<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/16962)
<!-- Reviewable:end -->
In a similar way to Position, now specified and computed gradients share
a common Gradient type defined in style::values::generics::image.
This allows us to reuse most code for many style traits like ToCss,
HasViewportPercentage and ToComputedValue.
The test changes are the fallout of the disappearance of AngleOrCorner::None,
which align our code to the spec for serialisation, where components that can
be omitted should be omitted.
We need another flag that represents allow-negative-number for SMIL, so
this enum will also comprise the another parsing mode that allows negative number.
scriptlevel is a property that affects how font-size is inherited. If scriptlevel is
+1, for example, it will inherit as the script size multiplier times
the parent font. This does not affect cases where the font-size is
explicitly set.
However, this transformation is not allowed to reduce the size below
scriptminsize. If this inheritance will reduce it to below
scriptminsize, it will be set to scriptminsize or the parent size,
whichever is smaller (the parent size could be smaller than the min size
because it was explicitly specified).
Now, within a node that has inherited a font-size which was
crossing scriptminsize once the scriptlevel was applied, a negative
scriptlevel may be used to increase the size again.
This should work, however if we have already been capped by the
scriptminsize multiple times, this can lead to a jump in the size.
For example, if we have text of the form:
huge large medium small tiny reallytiny tiny small medium huge
which is represented by progressive nesting and scriptlevel values of
+1 till the center after which the scriptlevel is -1, the "tiny"s should
be the same size, as should be the "small"s and "medium"s, etc.
However, if scriptminsize kicked it at around "medium", then
medium/tiny/reallytiny will all be the same size (the min size).
A -1 scriptlevel change after this will increase the min size by the
multiplier, making the second tiny larger than medium.
Instead, we wish for the second "tiny" to still be capped by the script
level, and when we reach the second "large", it should be the same size
as the original one.
We do this by cascading two separate font sizes. The font size (mSize)
is the actual displayed font size. The unconstrained font size
(mScriptUnconstrainedSize) is the font size in the situation where
scriptminsize never applied.
We calculate the proposed inherited font size based on scriptlevel and
the parent unconstrained size, instead of using the parent font size.
This is stored in the node's unconstrained size and will also be stored
in the font size provided that it is above the min size.
All of this only applies when inheriting. When the font size is
manually set, scriptminsize does not apply, and both the real and
unconstrained size are set to the explicit value. However, if the font
size is manually set to an em or percent unit, the unconstrained size
will be set to the value of that unit computed against the parent
unconstrained size, whereas the font size will be set computing against
the parent font size.
MozReview-Commit-ID: 820BIWqno3L
Upgrade to rustc 1.18.0-nightly (5f13a3b54 2017-04-15)
This version enables [struct field reordering][1] which brings the size of the types for specified values of some CSS properties under the threshold such that they shouldn’t be boxed anymore, making unit tests fail.
Simply unboxing them moves the test failure to Stylo’s unit tests, since the stable compiler used in that case does not do field re-ordering. Therefore, we manually reorder a couple fields to effectively bring this optimization to older compilers for a few specific types.
[1]: https://github.com/rust-lang/rust/pull/40377
<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/16473)
<!-- Reviewable:end -->
Support non-negative parsing of lengths for Either<Length, T> types
<!-- Please describe your changes on the following line: -->
Implemented a generic `impl<T> Either<Length, T>` which has a `parse_non_negative_length` method.
---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix#16423
<!-- Either: -->
- [x] These changes do not require tests because this functionality makes code more modular and doesn't change any existing implementation.
<!-- Also, please make sure that "Allow edits from maintainers" checkbox is checked, so that we can help you if you get stuck somewhere along the way.-->
<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->
<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/16478)
<!-- Reviewable:end -->
This version enables [struct field reordering][1] which brings the size
of the types for specified values of some CSS properties under the threshold
such that they shouldn’t be boxed anymore, making unit tests fail.
Simply unboxing them moves the test failure to Stylo’s unit tests,
since the stable compiler used in that case does not do field re-ordering.
Therefore, we manually reorder a couple fields to effectively bring this
optimization to older compilers for a few specific types.
[1]: https://github.com/rust-lang/rust/pull/40377
To make it possible to check the rule type when parsing lengths, we need to pass
the `ParserContext` down through many layers to the place where length units are
parsed.
This change leaves it unused, so it's only to prepare for the next change.
MozReview-Commit-ID: 70YwtcCxnWw
