boolean isRelevant) constructor

Allows to use the new JDT StringBuffer to StringBuilder cleanup in JST
view code.

Change-Id: I31d18b013d540f816e9f2956590e41a182d2e12d
Signed-off-by: Lars Vogel <Lars.Vogel@vogella.com>
Reviewed-on: https://git.eclipse.org/r/c/jdt/eclipse.jdt.ui/+/182330
Tested-by: JDT Bot <jdt-bot@eclipse.org>
Tested-by: Jeff Johnston <jjohnstn@redhat.com>
Reviewed-by: Jeff Johnston <jjohnstn@redhat.com>