Make SELENIUM_OVERRIDES available to override from base package.json

[philippw]

I'm trying to convince wct-local to download selenium and its drivers via an internal Artifactory server instead of directly from GitHub. selenium-standalone supports this via its baseURL settings.

However, as selenium-standalone is a transitive dependency of wct-local I cannot override the default values.
Fortunately, there's the scripts/postinstall.js and its SELENIUM_OVERRIDES, which would allow for excatly that, would it not be the case that it only ever parses settings from wct-local's own package.json`.

Can we change the lookup path from ../package.json to ../../../package.json to be able to override the Selenium settings from the base package.json?

[nicojs]

I think using an environment variable for this is more common for these types of features. Also, this issue is reported to the wrong git repository. I think it should be reported to wct-local

See this file: https://github.com/Polymer/wct-local/blob/master/scripts/postinstall.js

[philippw]

Moved to the correct issues tracker. Closing this bug now.