Simplify JSType#getTypesUnder(Shallow)?Inequality
Simplify JSType#getTypesUnder(Shallow)?Inequality

An earlier CL ([] was slightly overcomplicated.  With the realization that only non-union types can show up after the union types have been filtered out, we can actually make the result even simpler than it was originally.

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google/closure-compiler,google/closure-compiler,monetate/closure-compiler,google/closure-compiler,ChadKillingsworth/closure-compiler,monetate/closure-compiler,ChadKillingsworth/closure-compiler,google/closure-compiler,Yannic/closure-compiler,nawawi/closure-compiler,Yannic/closure-compiler,ChadKillingsworth/closure-compiler,nawawi/closure-compiler,monetate/closure-compiler,Yannic/closure-compiler,vobruba-martin/closure-compiler,nawawi/closure-compiler,ChadKillingsworth/closure-compiler,vobruba-martin/closure-compiler,vobruba-martin/closure-compiler,Yannic/closure-compiler,nawawi/closure-compiler,monetate/closure-compiler,vobruba-martin/closure-compiler