Remove unused chain from install.js.

Author: reid

lib/install.js

@@ -25,7 +25,6 @@ var registry = require("./utils/registry")
   , readJson = require("./utils/read-json")
   , log = require("./utils/log")
   , path = require("path")
-  , chain = require("./utils/chain")
   , fs = require("./utils/graceful-fs")
   , cache = require("./cache")
   , asyncMap = require("./utils/async-map")