Warn if an action is rejected with a syntax error

[nhunzaker]

Maybe in strict mode only, it would be neat to check to see if the error passed to the promise form is a standard error, like:

function promiseAction () {
  return new Promise(function (resolve, reject) {
    // The error is right here, can you see it?
    resolev('body')  
  })
}

This is from a difficult to track down error on a current project. Things to figure out:

• Was it just our Promise library? Or did Microcosm do something to prevent Chrome from surfacing the uncaught error?
• Is this just a rabbit hole? Should we only check for SyntaxError, TypeError, or ReferenceError?
• Is this too helpful? Should we consider an option to mute this sort of thing?

cc @solomonhawk