Make the sw imports sorted

[el]

R: @jeffposnick @philipwalton

Fixes #1972

Description of what's changed/fixed.
Added sorting before generating a hash

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[el]

I signed it!

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[coveralls]

Coverage decreased (-1.4%) to 76.864% when pulling 614df72 on el:master into d85aea0 on GoogleChrome:master.

[jeffposnick]

We unfortunately need to update the hashes hardcoded in the unit tests when there's a change that alters the webpack plugin's output.

I'll push a commit to the branch in this PR with the necessary updates.

[jeffposnick]

Thanks for your contribution!

[el]

Thanks for handling the tests. Can you publish a new version to npm? (We have a package layout file that lists all the files and this makes precache file change the name randomly)

[jeffposnick]

Likely within the next week or so—we do try to batch up the changes a bit in between releases.

[el]

Ohh, that works thanks. I will just disable the chunks until then ;)