Race condition in test suite

[kristoferbaxter]

What's the issue?

Test suite intermittently fails when using experimentalCodeSplitting, occasionally testing dynamically imported members instead of the entry point.

  - `export function handleImport(){return 2};␊
  + `export function exported(){import("./dynamic-imported.js").then(function(a){return a.handleImport()})};␊
    `

How do we reproduce the issue?

npm run test a few times will cause the error.

[kristoferbaxter]

Addressed in #105.