stylo: Bug 1390039 - Implement compute_distance for mismatched transform lists.
Implement ComputeSquaredDistance for mismatched transform lists.
In order to do this, we have to convert a transform list into a 3d matrix,
so I move the code from layout module into style module for reusing it.
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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix [Bug 1390039](https://bugzilla.mozilla.org/show_bug.cgi?id=1390039).
- [X] These changes do not require tests because this is a Gecko feature and I add many tests in Gecko already.
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We could use this method to convert a TransformList into a Matrix, and
use this matrix for computing distance for Stylo and rendering the transform
for Servo.
This is an equivalent of nsStyleTransformMatrix::ReadTransforms in Gecko.
