make browser tests use separate windows https://codereview.appspot.com/7221069
make browser tests use separate windows
https://codereview.appspot.com/7221069

the caja runtime recently changed in some way that makes it
consume significantly more memory, and what's worse it does so
in a way that seems to not get freed in firefox when we run
browser tests.  firefox eventually uses like 2G or so before
it finishes.  this might be something specific about how we keep
loaidng the same page but with different query parameters.

this change is a short-term mitigation.  it makes each browser
test open a new window (in Chrome it's a new tab), which doesn't
really solve the issue, but lets tests finish with less memory.

I've also increased the waiting-for-progress timeout from 25s
to 40s, because testTargetAttributePresets in Chrome on my
laptop regularly works for about 30s without apparent progress

R=kpreid2


git-svn-id: eb21526166532bd3afc2c1499c0cf105ce815f5a@5243 360991c0-9f3b-0410-ba87-8b362a00edf4

wishabi/caja-1,initaldk/caja,wishabi/caja-1,cepm-nate/caja,wishabi/caja-1,jasvir/caja,jasvir/caja,googlearchive/caja,initaldk/caja,cepm-nate/caja,jasvir/caja,wishabi/caja-1,cepm-nate/caja,initaldk/caja,jasvir/caja,googlearchive/caja,jasvir/caja,cepm-nate/caja,initaldk/caja,cepm-nate/caja,initaldk/caja,googlearchive/caja,cepm-nate/caja,initaldk/caja,wishabi/caja-1,googlearchive/caja,googlearchive/caja,jasvir/caja,wishabi/caja-1,googlearchive/caja