Issue 1370 - Suppress "Uncaught ReferenceError: ext is not defined"
This error came started showing up in Chrome 37 and will probably be fixed in Chrome 40 (https://crbug.com/416907).

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extra : amend_source : 9a2e972297f558bff60768abf08c645246f5017a
Issue 1370 - Slightly improved comment accompanying the previous change