specs for MethodOrProcHelper#render_or_call_method_or_proc_on
Fix for #3155
test fix for #3155
specs for MethodOrProcHelper#render_in_context
check the return of MethodOrProcHelper#render_or_call_method_or_proc_on and #render_in_context
Merge pull request #3158 from timoschilling/missing_specs

Missing specs for MethodOrProcHelper
Merge pull request #3156 from rottame/master

Fix for #3155