Created by: bsyk
Adjust the checkIfOnline check if in a corporate proxy environment
If the environment variable https_proxy is set, test that the proxy name is resolveable rather than 'registry.yarnpkg.com'.
Testing on a corporate network where proxies are required. Prior to change, installation fails as per #2832 (closed), post change installation works happily.
Before:
After with proxy set & required:
After with proxy not set, but required:
After with proxy set incorrectly:
