Bug 1090599 - Upgrade in-tree jsmin to release-2.0.11. r=gps

This updates to release-2.0.11 (sha1: 04374472ed18) from
https://bitbucket.org/dcs/jsmin/.
Bug 1039902 - Minify the Fennec JS code in automation. r=glandium

This patch adds a SpiderMonkey jsshell binary via tooltool and arranges
for it to be used in automation (more specifically, whenever JS_BINARY
is defined).

We'd prefer to build a host SpiderMonkey jsshell, but that's not trivial
right now; and we'd prefer to use a minifier better than the existing
Python jsmin (possibly written in JavaScript), but one step at a time.