The reload button in DocHeader within the viewpage backend module
should not reload the whole content area but only the iframe location.

Change-Id: I03e2e6fe0b1be07465035f8e19da931515bb767c
Fixes: #37916
Releases: 6.0
Reviewed-on: http://review.typo3.org/11946
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn
Reviewed-by: Georg Ringer
Tested-by: Georg Ringer