short_name shouldn't be required

[jakearchibald]

https://github.com/GoogleChrome/lighthouse/blob/master/lighthouse-core/audits/webapp-install-banner.js#L49

If the name property is short enough, you don't need short_name. The test should reflect this.

This is either a regression of #348, or wasn't fixed.

[jakearchibald]

Also in https://github.com/GoogleChrome/lighthouse/blob/master/lighthouse-core/audits/manifest-short-name-length.js

[patrickhulce]

Yeah looks like in the refactor into https://github.com/GoogleChrome/lighthouse/blob/master/lighthouse-core/gather/computed/manifest-values.js the fixed logic stopped being used even though the code is still there, looks like all we need to do is replace hasShortName with shortNameLength?

[paulirish]

related bit: #686