Removing unnecessary source attribute added in 6eaf842a. Including the source attribute can cause an extra request to be made to the current page URL when the iFrame is included on the page. See issue #1622.
Merge branch 'patch/io-upload-iframe-src' into release/3.14.1-1-odl

* patch/io-upload-iframe-src:
  Removing unnecessary source attribute added in 6eaf842a. Including the source attribute can cause an extra request to be made to the current page URL when the iFrame is included on the page. See issue #1622.