Polymer/core-ajax — pull request #52 by majidfn (2014-12-09 13:04:15+00:00)
Title: Removing the condition which would return status as successful

If there is no status on the call, the call should not be considered as successful.
For example when the back-end server is not responding although there was a `ERR_CONNECTION_RESET` but still the `core-response` was being fire instead of `core-error`. This was as the result of status being `0` and and `!0` would return `true` for `isSuccess`