fix(Dropdown): isEqual over shallowEqual for props

[chrisjbrown]

fixes #2243

Component on componentWillReceiveProps will always run setSelectedIndex because shallowEqual on two objects internally runs object.is(a, b) to compare objects which will always be false because nextProps.options and this.props.options are not the same object

[codecov-io]

Codecov Report

❗ No coverage uploaded for pull request base (master@de69da9). Click here to learn what that means.
The diff coverage is 100%.

@@            Coverage Diff            @@
##             master    #2252   +/-   ##
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  Coverage          ?   99.73%           
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  Files             ?      152           
  Lines             ?     2652           
  Branches          ?        0           
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  Hits              ?     2645           
  Misses            ?        7           
  Partials          ?        0

Impacted Files	Coverage Δ
src/modules/Dropdown/Dropdown.js	100% <100%> (ø)

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[levithomason]

Let's get a test here that fails with the workflow reported in the issue. This way we don't hit the regression again.

isEqual was removed as part of the lodash optimizations as it is a very slow and heavy method. We can use it here if we must, but I'd like to ensure there is a test that catches the failing behavior.

[chrisjbrown]

Added UT for when props are updated with options that are the same and when props are updated with new options.

[levithomason]

Awesome, thank you very much @chrisjbrown!

[levithomason]

Released in [email protected]