Remove rust-encoding from geckolib.

It wasn’t used, gecko always passes UTF-8 for parsing stylesheets.

components/style/encoding_support.rs

@@ -0,0 +1,89 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//! Parsing stylesheets from bytes (not `&str`).
+
+extern crate encoding;
+
+use cssparser::{stylesheet_encoding, EncodingSupport};
+use error_reporting::ParseErrorReporter;
+use media_queries::MediaList;
+use parser::ParserContextExtraData;
+use self::encoding::{EncodingRef, DecoderTrap};
+use servo_url::ServoUrl;
+use std::str;
+use stylesheets::{Stylesheet, StylesheetLoader, Origin};
+
+struct RustEncoding;
+
+impl EncodingSupport for RustEncoding {
+    type Encoding = EncodingRef;
+
+    fn utf8() -> Self::Encoding {
+        encoding::all::UTF_8
+    }
+
+    fn is_utf16_be_or_le(encoding: &Self::Encoding) -> bool {
+        matches!(encoding.name(), "utf-16be" | "utf-16le")
+    }
+
+    fn from_label(ascii_label: &[u8]) -> Option<Self::Encoding> {
+        str::from_utf8(ascii_label).ok().and_then(encoding::label::encoding_from_whatwg_label)
+    }
+}
+
+fn decode_stylesheet_bytes(css: &[u8], protocol_encoding_label: Option<&str>,
+                           environment_encoding: Option<EncodingRef>)
+                           -> (String, EncodingRef) {
+    let fallback_encoding = stylesheet_encoding::<RustEncoding>(
+        css, protocol_encoding_label.map(str::as_bytes), environment_encoding);
+    let (result, used_encoding) = encoding::decode(css, DecoderTrap::Replace, fallback_encoding);
+    (result.unwrap(), used_encoding)
+}
+
+impl Stylesheet {
+    /// Parse a stylesheet from a set of bytes, potentially received over the
+    /// network.
+    ///
+    /// Takes care of decoding the network bytes and forwards the resulting
+    /// string to `Stylesheet::from_str`.
+    pub fn from_bytes(bytes: &[u8],
+                      base_url: ServoUrl,
+                      protocol_encoding_label: Option<&str>,
+                      environment_encoding: Option<EncodingRef>,
+                      origin: Origin,
+                      media: MediaList,
+                      stylesheet_loader: Option<&StylesheetLoader>,
+                      error_reporter: &ParseErrorReporter,
+                      extra_data: ParserContextExtraData)
+                      -> Stylesheet {
+        let (string, _) = decode_stylesheet_bytes(
+            bytes, protocol_encoding_label, environment_encoding);
+        Stylesheet::from_str(&string,
+                             base_url,
+                             origin,
+                             media,
+                             stylesheet_loader,
+                             error_reporter,
+                             extra_data)
+    }
+
+    /// Updates an empty stylesheet with a set of bytes that reached over the
+    /// network.
+    pub fn update_from_bytes(existing: &Stylesheet,
+                             bytes: &[u8],
+                             protocol_encoding_label: Option<&str>,
+                             environment_encoding: Option<EncodingRef>,
+                             stylesheet_loader: Option<&StylesheetLoader>,
+                             error_reporter: &ParseErrorReporter,
+                             extra_data: ParserContextExtraData) {
+        let (string, _) = decode_stylesheet_bytes(
+            bytes, protocol_encoding_label, environment_encoding);
+        Self::update_from_str(existing,
+                              &string,
+                              stylesheet_loader,
+                              error_reporter,
+                              extra_data)
+    }
+}