add missing guards to StringExtensions
add missing guards to StringExtensions

modulexcite/xbehave.net,mvalipour/xbehave.net,xbehave/xbehave.net,adamralph/xbehave.net,mvalipour/xbehave.net,hitesh97/xbehave.net,modulexcite/xbehave.net,hitesh97/xbehave.net