[BUGFIX] Avoid double wrap in css_styled_content

Since TYPO3 6.0, USER objects have stdWrap property. The
various render methods of css_styled_content still call
stdWrap themselves, resulting in a double wrap.

Remove the stdWrap calls in css_styled_content render methods.

Resolves: #49051
Releases: 6.0, 6.1, 6.2
Change-Id: I3092990a4d1efb12597dc543c222a727135d63ec
Reviewed-on: https://review.typo3.org/21364
Reviewed-by: Francois Suter
Tested-by: Francois Suter