chore: install cssbundling rails and set up compilation

spec/dummy/node_modules/string-width/index.d.ts

@@ -0,0 +1,29 @@
+declare const stringWidth: {
+	/**
+	Get the visual width of a string - the number of columns required to display it.
+
+	Some Unicode characters are [fullwidth](https://en.wikipedia.org/wiki/Halfwidth_and_fullwidth_forms) and use double the normal width. [ANSI escape codes](https://en.wikipedia.org/wiki/ANSI_escape_code) are stripped and doesn't affect the width.
+
+	@example
+	```
+	import stringWidth = require('string-width');
+
+	stringWidth('a');
+	//=> 1
+
+	stringWidth('古');
+	//=> 2
+
+	stringWidth('\u001B[1m古\u001B[22m');
+	//=> 2
+	```
+	*/
+	(string: string): number;
+
+	// TODO: remove this in the next major version, refactor the whole definition to:
+	// declare function stringWidth(string: string): number;
+	// export = stringWidth;
+	default: typeof stringWidth;
+}
+
+export = stringWidth;