isaacs/core-util-is — pull request #3 by substack (2014-03-04 21:49:12+00:00)
Title: fix for es<5 not having Array.isArray()

I'm trying to get readable-stream to work in old browsers and this module is one of its downstream dependencies. This patch just defers to the toString '[object Array]' trick for isArray if Array.isArray isn't present.