Adding upstream version 115.7.0esr.upstream/115.7.0esr

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

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diff --git a/third_party/rust/cssparser/README.md b/third_party/rust/cssparser/README.md
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+rust-cssparser
+==============
+
+[![Build Status](https://github.com/servo/rust-cssparser/actions/workflows/main.yml/badge.svg)](https://github.com/servo/rust-cssparser/actions)
+
+[Documentation](https://docs.rs/cssparser/)
+
+Rust implementation of
+[CSS Syntax Module Level 3](https://drafts.csswg.org/css-syntax/)
+
+
+Overview
+--------
+
+Parsing CSS involves a series of steps:
+
+* When parsing from bytes,
+  (e.g. reading a file or fetching an URL from the network,)
+  detect the character encoding
+  (based on a `Content-Type` HTTP header, an `@charset` rule, a BOM, etc.)
+  and decode to Unicode text.
+
+  rust-cssparser does not do this yet and just assumes UTF-8.
+
+  This step is skipped when parsing from Unicode, e.g. in an HTML `<style>` element.
+
+* Tokenization, a.k.a. lexing.
+  The input, a stream of Unicode text, is transformed into a stream of *tokens*.
+  Tokenization never fails, although the output may contain *error tokens*.
+
+* This flat stream of tokens is then transformed into a tree of *component values*,
+  which are either *preserved tokens*,
+  or blocks/functions (`{ … }`, `[ … ]`, `( … )`, `foo( … )`)
+  that contain more component values.
+
+  rust-cssparser does this at the same time as tokenization:
+  raw tokens are never materialized, you only get component values.
+
+* Component values can then be parsed into generic rules or declarations.
+  The header and body of rules as well as the value of declarations
+  are still just lists of component values at this point.
+  See [the `Token` enum](src/tokenizer.rs) for the data structure.
+
+* The last step of a full CSS parser is
+  parsing the remaining component values
+  into [Selectors](https://drafts.csswg.org/selectors/),
+  specific CSS properties, etc.
+
+  By design, rust-cssparser does not do this last step
+  which depends a lot on what you want to do:
+  which properties you want to support, what you want to do with selectors, etc.
+
+  It does however provide some helper functions to parse [CSS colors](src/color.rs)
+  and [An+B](src/nth.rs) (the argument to `:nth-child()` and related selectors.
+
+  See [Servo’s `style` crate](https://github.com/servo/servo/tree/master/components/style)
+  for an example of a parser based on rust-cssparser.