chore(performance): optimize regressed for..of and array destructuring performance #4080
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One of the issues we uncovered in #3648 is that upgrading to ES6 output maintained the
for..ofand array destructuring in our bundles which leads to a pretty considerable performance regression. This changes our build step to account for these less performant syntaxes and transforms them.There is more low hanging fruit that can be optimised like the custom accumulatormap/... however starting with a quick win. The babel plugin also still leverages the iterator spec for non-array for loops, it optimises what it can
Fixes #3648
The performance implication would be higher if we did something akin to #3687