[BUGFIX] RTE link insertion issues with IE9

Problem: inRange method not supported by standard range object used
with IE9.
Solution: Use standards-based method with IE9

Note: Thanks to Johannes Pfeiffer

Change-Id: Iccf230e6103e72953e49eb1a4dde967f3e65a5b7
Releases: 4.7, 6.0
Resolve: #38300
Reviewed-on: http://review.typo3.org/12422
Reviewed-by: Stanislas Rolland
Tested-by: Stanislas Rolland