Bump JS version to 2.43.4.  For versions 2.43.1-3, the npm registry was
recording an incorrect shasum which causes subsequent npm installs to fail on
those versions. npm requires a unique version for each published version, and
it supports semantic versioning 2.0 (http://semver.org/), which is why we are
now on 2.43.4.

An issue has been filed with npm about the incorrect shasum:
https://github.com/npm/npm/issues/6179

Fixes issue 7890.