We need to use enum instead of Either since we can't interpolate stroke-* between
unitless length and unit length(e.g. '5' -> '10px').
This coomit make following:
* Introduce SVGLengthOrPercentageOrNumber on computed and specified values.
* Make SVGLengthOrPercentageOrNumber animatable.
* Make stroke-dasharray not-accumulate.
Don't allow interpolating 'fill:none' with 'fill:none'
From [Gecko bug 1390364](https://bugzilla.mozilla.org/show_bug.cgi?id=1390364).
In SMIL we don't expect the 'none' value of the 'fill' property to be additive and hence the following animation should have no effect:
```svg
<rect width="100" height="100" y="100" fill="blue">
<animate attributeName="fill" dur="3s" from="red" by="none"/>
</rect>
```
Although SMIL doesn't make this entirely clear, [it says](https://www.w3.org/TR/smil-animation/#AnimFuncValues) that "by animation" and "from-by animation" may only be used "with attributes that support addition (e.g. most numeric attributes)" and [SVG says](https://www.w3.org/TR/SVG11/animate.html#AnimationAttributesAndProperties) that `<paint>`s are "only additive if each value can be converted to an RGB color". As a result, the animation above should have no effect.
By extrapolation, animating from 'none' by 'none' should also have no effect:
```svg
<rect width="100" height="100" y="100" fill="blue">
<animate attributeName="fill" dur="3s" from="none" by="none"/>
</rect>
```
However, in Servo's interpolation of `<paint>`s we special case the interpolation and addition of 'none' such that if both values are 'none' it is allowed.
We should disallow this in order to produce the expected behavior and in order to match Gecko's behavior.
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This moves us to clear on rebuild, which allows us to remove yet another place
where we track stylist dirtiness.
Bug: 1390255
Reviewed-by: heycam
MozReview-Commit-ID: nihQbUAbh8
Signed-off-by: Emilio Cobos Álvarez <emilio@crisal.io>
In SMIL we don't expect the 'none' value of the 'fill' property to be
additive and hence the following animation should have no effect:
<rect width="100" height="100" y="100" fill="blue">
<animate attributeName="fill" dur="3s" from="red" by="none"/>
</rect>
Although SMIL doesn't make this entirely clear, [1] says that "by
animation" and "from-by animation" may only be used "with attributes
that support addition (e.g. most numeric attributes)" and [2] says that
<paint>s are "only additive if each value can be converted to an RGB
color". As a result, the animation above should have no effect.
By extrapolation, animating from 'none' by 'none' should also have no
effect:
<rect width="100" height="100" y="100" fill="blue">
<animate attributeName="fill" dur="3s" from="none" by="none"/>
</rect>
However, in Servo's interpolation of <paint>s we special case the
interpolation and addition of 'none' such that if both values are 'none'
it is allowed.
We should disallow this in order to produce the expected behavior and in
order to match Gecko's behavior.
[1] https://www.w3.org/TR/smil-animation/#AnimFuncValues
[2] https://www.w3.org/TR/SVG11/animate.html#AnimationAttributesAndProperties
Make emtpy rule can be inserted into rule tree
<!-- Please describe your changes on the following line: -->
We really want to ensure empty rule nodes appear in the rule tree for devtools, this condition ensures that if we find an empty rule node, we insert it at the normal level.
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- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix [Bug 1384802](https://bugzilla.mozilla.org/show_bug.cgi?id=1384802)
<!-- Either: -->
- [ ] There are tests for these changes OR
- [X] These changes do not require tests because of the test cases are in Gecko.
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Bindgen bitfield enums don't work as return values with the Linux 32-bit ABI at
the moment because they wrap the value in a struct.
This causes the Rust side to believe the callee expects space for the struct
return value, while C++ believes it's just an integer value.
MozReview-Commit-ID: FRBqlZuMiAR
Make content animatable
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- [X] `./mach test-tidy` does not report any errors
<!-- Either: -->
- [X] There are tests for these changes. The test codes are patch part 3 and 4 in https://bugzilla.mozilla.org/show_bug.cgi?id=1382136
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Don't convert zero component value to 'auto' in clone__moz_image_region.
Currently Gecko treats 'auto' component value as zero for animation.
<!-- Please describe your changes on the following line: -->
https://bugzilla.mozilla.org/show_bug.cgi?id=1387951
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- [X] `./mach test-tidy` does not report any errors
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For CSS Transitions we want this case to return Err() so we know that the two
values are not interpolable.
For CSS Animations/Web Animations we implement discrete animation as the
fallback behavior when Err() is returned.
column-count should be greater than or equal to 1. Also it should be less than
or equal to nsStyleColumn_kMaxColumnCount since we limit it in
set_column_count().
