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/stylelint/lib/utils/validateOptions.js b/node_modules/stylelint/lib/utils/validateOptions.js
new file mode 100644
index 0000000..a315839
--- /dev/null
+++ b/node_modules/stylelint/lib/utils/validateOptions.js
@@ -0,0 +1,171 @@
+'use strict';
+
+const _ = require('lodash');
+
+const ignoredOptions = ['severity', 'message'];
+
+/** @typedef {{possible: any, actual: any, optional: boolean}} Options */
+
+/**
+ * Validate a rule's options.
+ *
+ * See existing rules for examples.
+ *
+ * @param {import('stylelint').PostcssResult} result - postcss result
+ * @param {string} ruleName
+ * @param {...Options} optionDescriptions - Each optionDescription can
+ *   have the following properties:
+ *   	- `actual` (required): the actual passed option value or object.
+ *   	- `possible` (required): a schema representation of what values are
+ *      valid for those options. `possible` should be an object if the
+ *      options are an object, with corresponding keys; if the options are not an
+ *      object, `possible` isn't, either. All `possible` value representations
+ *      should be **arrays of either values or functions**. Values are === checked
+ *      against `actual`. Functions are fed `actual` as an argument and their
+ *      return value is interpreted: truthy = valid, falsy = invalid.
+ *    - `optional` (optional): If this is `true`, `actual` can be undefined.
+ * @return {boolean} Whether or not the options are valid (true = valid)
+ */
+
+module.exports = function (result, ruleName, ...optionDescriptions) {
+	let noErrors = true;
+
+	optionDescriptions.forEach((optionDescription) => {
+		validate(optionDescription, ruleName, complain);
+	});
+
+	/**
+	 * @param {string} message
+	 */
+	function complain(message) {
+		noErrors = false;
+		result.warn(message, {
+			stylelintType: 'invalidOption',
+		});
+		_.set(result, 'stylelint.stylelintError', true);
+	}
+
+	return noErrors;
+};
+
+/**
+ * @param {Options} opts
+ * @param {string} ruleName
+ * @param {(s: string) => void} complain
+ */
+function validate(opts, ruleName, complain) {
+	const possible = opts.possible;
+	const actual = opts.actual;
+	const optional = opts.optional;
+
+	if (actual === null || _.isEqual(actual, [null])) {
+		return;
+	}
+
+	const nothingPossible =
+		possible === undefined || (Array.isArray(possible) && possible.length === 0);
+
+	if (nothingPossible && actual === true) {
+		return;
+	}
+
+	if (actual === undefined) {
+		if (nothingPossible || optional) {
+			return;
+		}
+
+		complain(`Expected option value for rule "${ruleName}"`);
+
+		return;
+	}
+
+	if (nothingPossible) {
+		if (optional) {
+			complain(
+				`Incorrect configuration for rule "${ruleName}". Rule should have "possible" values for options validation`,
+			);
+
+			return;
+		}
+
+		complain(`Unexpected option value "${String(actual)}" for rule "${ruleName}"`);
+
+		return;
+	}
+
+	// If `possible` is a function ...
+	if (_.isFunction(possible)) {
+		if (!possible(actual)) {
+			complain(`Invalid option "${JSON.stringify(actual)}" for rule ${ruleName}`);
+		}
+
+		return;
+	}
+
+	// If `possible` is an array instead of an object ...
+	if (!_.isPlainObject(possible)) {
+		[].concat(actual).forEach((a) => {
+			if (isValid(possible, a)) {
+				return;
+			}
+
+			complain(`Invalid option value "${String(a)}" for rule "${ruleName}"`);
+		});
+
+		return;
+	}
+
+	// If actual is NOT an object ...
+	if (typeof actual !== 'object') {
+		complain(
+			`Invalid option value ${JSON.stringify(actual)} for rule "${ruleName}": should be an object`,
+		);
+
+		return;
+	}
+
+	Object.keys(actual).forEach((optionName) => {
+		if (ignoredOptions.includes(optionName)) {
+			return;
+		}
+
+		if (!possible[optionName]) {
+			complain(`Invalid option name "${optionName}" for rule "${ruleName}"`);
+
+			return;
+		}
+
+		const actualOptionValue = actual[optionName];
+
+		[].concat(actualOptionValue).forEach((a) => {
+			if (isValid(possible[optionName], a)) {
+				return;
+			}
+
+			complain(`Invalid value "${a}" for option "${optionName}" of rule "${ruleName}"`);
+		});
+	});
+}
+
+/**
+ * @param {any|Function} possible
+ * @param {any} actual
+ * @returns {boolean}
+ */
+function isValid(possible, actual) {
+	const possibleList = /** @type {Array<any|Function>} */ ([]).concat(possible);
+
+	for (let i = 0, l = possibleList.length; i < l; i++) {
+		const possibility = possibleList[i];
+
+		if (typeof possibility === 'function' && possibility(actual)) {
+			return true;
+		}
+
+		if (actual === possibility) {
+			return true;
+		}
+	}
+
+	return false;
+}