Don't include inline source maps in markdown preview scripts

extensions/markdown-language-features/webpack.config.js

@@ -21,9 +21,8 @@ module.exports = {
 	resolve: {
 		extensions: ['.tsx', '.ts', '.js']
 	},
-	devtool: 'inline-source-map',
 	output: {
 		filename: '[name].js',
 		path: path.resolve(__dirname, 'media')
 	}
-};
+};