[BUGFIX] PHP 5.4 unit test warnings

[BUGFIX] PHP 5.4 unit test warnings

PHP 5.4 throws warnings "Creating default object from empty value"
warnings if $foo->bar is accessed and $foo is not an object. This
is the case in several unit tests, especially if $GLOBALS['TSFE']
is accessed.

Fixes: #42612
Releases: 6.0

Change-Id: Ia330dfa96a8374ffc30908c968eafcf350bf79d0
Reviewed-on: http://review.typo3.org/16118
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn