Make shadow values share more code
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Make `text-shadow` reuse `Shadow` type directly.
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We convert ComputedOperation::{Accumulate, Interpolate}Matrix into gecko type
not on the main thread, so we cannot use nsCSSValueList_heap (which is not
thread safe so we cannot create it and destroy it on different threads).
Therefore, we use nsCSSValueSharedList to represent the cloned
from_list/to_list. In this patch, we also implement the reversing way,
i.e. Convert eCSSKeyword_{accumulate, interpolate}matrix into
{Accumulate, Interpolate}Matrix.
If we set the composite operation to accumulate, we may need to accumulate two
mismatched transform lists, and then to interpolate them. In order to
accumulate two mismatched transform lists, we also need the reference
box information, so use the same idea as that for interpolation. i.e.
use AccmulateMatrix to store it temporarily, and convert it into matrix
later.
We use this arm to store the interpolated result of two mismatched
transform lists, and we resolve it until we know the reference box size
(on Gecko side). The conversion from ComputedOperation::InterpolateMatrix
to eCSSKeyword_interpolatematrix will be implemented later in this patch series.
The pref `webgl.testing.context_creation_error` will cause creation of a new WebGLRenderingContext to fail, iff set to true.
Also update test expectation of `context_creation_error.html` to pass.
Ged rid of libfontconfig in Android
Libfontconfig dependency is causing huge startup times in Android (20 seconds on each page load!). On other platforms fontconfig caches are already available or can be prebuilt on installation scripts, but this can't be done on Android. Updating libfontconfig dependency doesn't fix the problem either.
This PR gets rid of libfontconfig in Android. It queries available fonts and variations from Android System font configuration files. Android doesn't provide an API to query system fonts until Android O (which is very far from the minimum API right now...)
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Stop parsing @supports rules before Delimiter::Bang
Fixes#15482
Shorthand parsing uses `parse_entirely`, so we have to ask it to stop before the `!important`.
An alternate fix is to not use `parse_entirely` there and ensuring that all callers of `PropertyDeclaration::parse_into()` check that the input is exhausted. Two of the three callers do that anyway because they check for `!important`.
We also weren't checking for the end of the parser for `CSS.supports()`.
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