Add stylelint dependency

This also adds CC-BY-4.0 to the list of accepted licenses.

DISABLE_THIRD_PARTY_CHECK=update dependencies

Bug: chromium:1083142
Change-Id: I8612de2fba52dae32eeb71af79d5aacfde52142b
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/2220097
Reviewed-by: Paul Lewis <aerotwist@chromium.org>
Commit-Queue: Mathias Bynens <mathias@chromium.org>
diff --git a/node_modules/clone-regexp/index.js b/node_modules/clone-regexp/index.js
new file mode 100644
index 0000000..24edae6
--- /dev/null
+++ b/node_modules/clone-regexp/index.js
@@ -0,0 +1,29 @@
+'use strict';
+const isRegexp = require('is-regexp');
+
+const flagMap = {
+	global: 'g',
+	ignoreCase: 'i',
+	multiline: 'm',
+	dotAll: 's',
+	sticky: 'y',
+	unicode: 'u'
+};
+
+module.exports = (regexp, options = {}) => {
+	if (!isRegexp(regexp)) {
+		throw new TypeError('Expected a RegExp instance');
+	}
+
+	const flags = Object.keys(flagMap).map(flag => (
+		(typeof options[flag] === 'boolean' ? options[flag] : regexp[flag]) ? flagMap[flag] : ''
+	)).join('');
+
+	const clonedRegexp = new RegExp(options.source || regexp.source, flags);
+
+	clonedRegexp.lastIndex = typeof options.lastIndex === 'number' ?
+		options.lastIndex :
+		regexp.lastIndex;
+
+	return clonedRegexp;
+};