Allow non-functions to be passed to Rollbar.wrap

[kmontag]

Rollbar.wrap currently returns a function that errors out immediately (with "has no method 'apply'") when passed a non-function. This causes errors when, for example, addEventListener is called with an object implementing EventListener (https://developer.mozilla.org/en-US/docs/Web/API/EventListener) rather than a plain function.

[brianr]

Thanks @kmontag! This looks good to me, will wait for the travis build to pass and then merge once @coryvirok can get some eyes on it.

To take this a step further in the EventListener case, do you think it would make sense to wrap the passed-in object's handleEvent method? (assuming the property exists and is a function)

[kmontag]

@brianr I thought about that, but was hesitant to modify the handleEvent method on the object directly. And creating a copy of the object to give to addEventListener would mean the copy and the original object could get out of sync.

Maybe it's enough to do something like https://github.com/kmontag/rollbar.js/commit/a193d0517a8eb42f790a2d780dd9f64f6adb7bad ? But I feel like there may be some edge cases I'm missing...

[coryvirok]

This looks good. I'll create a new release shortly.