Wrap console.trace for IE 10

IE 10 doesn't support console.trace ([source](https://developer.mozilla.org/en-US/docs/Web/API/console.trace#Browser_compatibility)), and will throw an error if you attempt to call it.

I've confirmed that this patch solves the problem in our own unit tests for PouchDB.  See also https://github.com/pouchdb/pouchdb/issues/2198).