spread concat cannot be converted to ecmascript3

[jimdigriz]

Using --language_out=ECMASCRIPT3 with closure pops up the following error:

../Open-Measurement-JSClients/src/common/logger.js:11: ERROR - [JSC_CANNOT_CONVERT] This code cannot be converted from ES6. "..." passed to a constructor (consider using --language_out=ES5)
        throw new Error('Could not complete the test successfully - ', ...args);
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

PR massages code so it can be converted to ECMASCRIPT3

[Prestonkayla5]

Using --language_out=ECMASCRIPT3 with closure pops up the following error:

../Open-Measurement-JSClients/src/common/logger.js:11: ERROR - [JSC_CANNOT_CONVERT] This code cannot be converted from ES6. "..." passed to a constructor (consider using --language_out=ES5)

        throw new Error('Could not complete the test successfully - ', ...args);

              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

PR massages code so it can be converted to ECMASCRIPT3