This fixes a significant performance issue with LaTeX rendering (and
other things that invoked node) where starting up node took a few
hundred milliseconds due to nvm initialization.
Tweaked by tabbott to avoid copying the node binary itself, instead
using a tiny wrapper script.
This is important primarily because it's possible a future version of
node will expect to find libraries/dependencies/etc. installed via NVM
at some path related to the path of the node binary itself, and that's
more guaranteed with this new model.
Fixes#4618.
NVM takes a specific node version and installs the node package and
a corresponding compatible npm package.
We use it in a somewhat hackish way to install node/npm globally with
a pinned version, since that's how we actually want to consume node in
our development environment.
Other details:
- Travis CI now is configured to use the version of node installed by
provision; the easiest way to do this was to sabotage the existing node
installation.
- jsdom is upgraded to a current version, which both requires recent
node and also is required for the tests to pass with recent node.
This fixes running the node tests on Xenial.
Fixes#1498.
[tweaked by tabbott]