Fix collapse with circular reference

[jhen0409]

This PR fix the bug for:

var foo = {};
foo.bar = foo;

var foo2 = [];
foo2[2] = foo2;

var foo3 = new Set([])
foo3.add(foo3)

Will convert to:

var foo = {bar:foo};

var foo2 = [,,foo2];

var foo3 = new Set([foo3])

It will get undefined for var, a ReferenceError for let and const.

I catched the problem with prop-types module.

[codecov]

Codecov Report

Merging #523 into master will increase coverage by 0.19%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #523      +/-   ##
==========================================
+ Coverage   83.06%   83.26%   +0.19%     
==========================================
  Files          34       34              
  Lines        2539     2539              
  Branches      907      908       +1     
==========================================
+ Hits         2109     2114       +5     
+ Misses        257      254       -3     
+ Partials      173      171       -2

Impacted Files	Coverage Δ
...gin-transform-inline-consecutive-adds/src/index.js	79.79% <100%> (ø)	⬆️
...sform-inline-consecutive-adds/src/set-collapser.js	83.78% <100%> (+5.4%)	⬆️
packages/babel-plugin-minify-simplify/src/index.js	80.74% <0%> (+0.12%)	⬆️
...e-consecutive-adds/src/array-property-collapser.js	82.6% <0%> (+4.34%)	⬆️

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[boopathi]

Good catch. But, this check should go into the checkReference call which is used above so it applies the fix for all collapsers.

[jhen0409]

You're right! I'll do it to checkReference.

[jhen0409]

It should not expect an array (as Line 44), so I change to args[0] made Set works with this PR.

[boopathi]

Isn't it better to place r === expr first for early exit ?