I'm not fond of this at all.

I'd prefer to use an option object as parameter:

```javascript
getResizedImgBlob({
  blob: blob to be resized,
  limit: target limit for the resize operation,
  limitDivider: 2,
  callback: function
});
```

Another possibility is to break getResizedImgBlob in 2 functions:
* first function (let's keep `getResizedImgBlob`) calculate the ratio from the limit, and call the second function with this calculated ratio as parameter
* second function (let's call it `resizeImageBlobWithRatio`) just get the ratio as a parameter.

This way we could directly call the second function from `ensureSizeLimit`.

What do you think ? My preference is the second possibility, because it keeps the external interface, and I still find it's clearer/easier to break this in 2 functions.