exp/cookiejar: add a test for canonicalHost errors.
exp/cookiejar: add a test for canonicalHost errors.

R=dr.volker.dobler
CC=golang-dev
https://codereview.appspot.com/7389048

dsriram/golang,dsriram/golang,gnanderson/go,gnanderson/go,tv42/old-go,dsriram/golang,dsriram/golang,gnanderson/go,dsriram/golang,gnanderson/go,apparentlymart/golang,apparentlymart/golang,dsriram/golang,apparentlymart/golang,apparentlymart/golang,pombredanne/go-deleteme,gnanderson/go,apparentlymart/golang,pombredanne/go-deleteme,pombredanne/go-deleteme,apparentlymart/golang,tv42/old-go,gnanderson/go,pombredanne/go-deleteme,tv42/old-go,tv42/old-go,pombredanne/go-deleteme,dsriram/golang,pombredanne/go-deleteme,tv42/old-go,pombredanne/go-deleteme,tv42/old-go,apparentlymart/golang,tv42/old-go,gnanderson/go