scala-js/scala-js — pull request #227 by sjrd (2014-02-08 00:06:15+00:00)
Title: Fix #224: undefined crashes string interpolation.

Behind the scenes, string interpolation uses a StringBuilder.
So StringBuilder should survive to both `null` and `undefined`,
the two only values in JavaScript which don't have a toString()
method.

This commit simply uses `"" + x`, which will be translated into
`"" + x` in JavaScript, which itself does what we want.