Update Stylelint and Postcss

R=jacktfranklin@chromium.org

Bug: none
Change-Id: I961be18530d3ccbc4efed0c2cda9bd603b14e27b
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/3372931
Reviewed-by: Jack Franklin <jacktfranklin@chromium.org>
Commit-Queue: Tim Van der Lippe <tvanderlippe@chromium.org>
diff --git a/node_modules/stylelint/lib/resolveConfig.js b/node_modules/stylelint/lib/resolveConfig.js
new file mode 100644
index 0000000..3ff990a
--- /dev/null
+++ b/node_modules/stylelint/lib/resolveConfig.js
@@ -0,0 +1,47 @@
+'use strict';
+
+const createStylelint = require('./createStylelint');
+const path = require('path');
+
+/**
+ * Resolves the effective configuation for a given file. Resolves to `undefined`
+ * if no config is found.
+ * @param {string} filePath - The path to the file to get the config for.
+ * @param {Pick<
+ *   import('stylelint').LinterOptions,
+ *   | 'cwd'
+ *   | 'config'
+ *   | 'configBasedir'
+ *   | 'configFile'
+ * >} [options] - The options to use when creating the Stylelint instance.
+ * @returns {Promise<import('stylelint').Config | undefined>}
+ */
+module.exports = async function resolveConfig(
+	filePath,
+	{ cwd = process.cwd(), config, configBasedir, configFile } = {},
+) {
+	if (!filePath) {
+		return undefined;
+	}
+
+	const stylelint = createStylelint({
+		config,
+		configFile,
+		configBasedir,
+		cwd,
+	});
+
+	const absoluteFilePath = !path.isAbsolute(filePath)
+		? path.join(cwd, filePath)
+		: path.normalize(filePath);
+
+	const configSearchPath = stylelint._options.configFile || absoluteFilePath;
+
+	const resolved = await stylelint.getConfigForFile(configSearchPath, absoluteFilePath);
+
+	if (!resolved) {
+		return undefined;
+	}
+
+	return resolved.config;
+};