Consolidate build steps
Consolidate build steps

It’s generally good practice to combine multiple `RUN` commands that
form a single logical operation into a single `RUN` command with
multiple shell statements therein. This avoids creating unnecessary
intermediate build layers, thus making build caching more efficient.

Specifically we combine:

* Steps to add Google’s apt signing key, add Google’s apt repository,
  update all dependencies, and install Chrome
* Steps to configure Bower and NPM respectively to run as root

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