Async codemod introduces improper awaits and does not create async anonymous function contexts

[kliph-gladly]

Running the async codemod on the following code

const foo = function() {
  mySyncFunctionDoesNotReturnAPromiseOrEvenExist();
};

produces

const foo = function() {
  await mySyncFunctionDoesNotReturnAPromiseOrEvenExist();
};

This is syntactically incorrect for two reasons.

• The outer function context foo is not async so it doesn't make sense to use await within it.
• The function called in the inner scope mySyncFunctionDoesNotReturnAPromiseOrEvenExist does not return a Promise, so it doesn't make sense to use await.