Squashed 'lib/js2-mode/' changes from 714dca5..2c27e3e

2c27e3e Make comment vars buffer-local
b06f31f Update `js2-concat-multiline-strings' docstring

git-subtree-dir: lib/js2-mode
git-subtree-split: 2c27e3eb847ccbfd494d23d61098610c87d21804
Merge commit 'c20d8d85c27fd69289c41b713e9d0426c89ed059'