We can only set resource constraints before the isolate is initialized.
Since in the future, we want to initialize isolates at construction
time, we need to set constraints there.

It's possible to later modify the stack limit, so introduce an
Isolate::SetStackLimit method for that.

The SetResourceConstraints method will be deprecated. Users should pass
ResourceConstraints to Isolate::New, and use Isolate::SetStackLimit to
later modify the stack limit.

BUG=none
R=svenpanne@chromium.org
LOG=y

Review URL: https://codereview.chromium.org/559993005

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23964 ce2b1a6d-e550-0410-aec6-3dcde31c8c00