Simplify buffer check

Co-authored-by: Jon Surrell <sirreal@users.noreply.github.com>

packages/dependency-extraction-webpack-plugin/lib/index.js

@@ -287,7 +287,7 @@ class DependencyExtractionWebpackPlugin {
 			// Prepare to look for magic comments, in order to decide whether
 			// `wp-polyfill` is needed.
 			const processContentsForMagicComments = ( content ) => {
-				if ( content.toString().includes( '/* wp:polyfill */' ) ) {
+				if ( content.includes( '/* wp:polyfill */' ) ) {
 					chunkStaticDeps.add( 'wp-polyfill' );
 				}
 			};