Make some attr values case-insensitive in selectors

https://bugzilla.mozilla.org/show_bug.cgi?id=1363531

components/selectors/build.rs

@@ -0,0 +1,75 @@
+/* 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/. */
+
+extern crate phf_codegen;
+
+use std::env;
+use std::fs::File;
+use std::io::{BufWriter, Write};
+use std::path::Path;
+
+fn main() {
+    let path = Path::new(&env::var("OUT_DIR").unwrap())
+        .join("ascii_case_insensitive_html_attributes.rs");
+    let mut file = BufWriter::new(File::create(&path).unwrap());
+
+    write!(&mut file, "{{ static SET: ::phf::Set<&'static str> = ",
+    ).unwrap();
+    let mut set = phf_codegen::Set::new();
+    for name in ASCII_CASE_INSENSITIVE_HTML_ATTRIBUTES.split_whitespace() {
+        set.entry(name);
+    }
+    set.build(&mut file).unwrap();
+    write!(&mut file, "; &SET }}").unwrap();
+}
+
+/// https://html.spec.whatwg.org/multipage/#selectors
+static ASCII_CASE_INSENSITIVE_HTML_ATTRIBUTES: &'static str = r#"
+    accept
+    accept-charset
+    align
+    alink
+    axis
+    bgcolor
+    charset
+    checked
+    clear
+    codetype
+    color
+    compact
+    declare
+    defer
+    dir
+    direction
+    disabled
+    enctype
+    face
+    frame
+    hreflang
+    http-equiv
+    lang
+    language
+    link
+    media
+    method
+    multiple
+    nohref
+    noresize
+    noshade
+    nowrap
+    readonly
+    rel
+    rev
+    rules
+    scope
+    scrolling
+    selected
+    shape
+    target
+    text
+    type
+    valign
+    valuetype
+    vlink
+"#;