Fix behavior of TextWriter.Write with null StringBuilder (#20451)
Fix behavior of TextWriter.Write with null StringBuilder (#20451)

With other overloads (including Write(object)) if you passed null it just wouldn't write anything out, so we shouldn't throw for the StringBuilder overload either.

Signed-off-by: dotnet-bot <03c4cb6107ae99956a7681f2c97ff7104809a2bd@microsoft.com>

ericstj/corefx,shimingsg/corefx,BrennanConroy/corefx,Jiayili1/corefx,mmitche/corefx,ViktorHofer/corefx,wtgodbe/corefx,ViktorHofer/corefx,BrennanConroy/corefx,ptoonen/corefx,shimingsg/corefx,ericstj/corefx,ptoonen/corefx,BrennanConroy/corefx,Jiayili1/corefx,wtgodbe/corefx,ViktorHofer/corefx,shimingsg/corefx,mmitche/corefx,ericstj/corefx,mmitche/corefx,ptoonen/corefx,ericstj/corefx,wtgodbe/corefx,ptoonen/corefx,ericstj/corefx,ericstj/corefx,ViktorHofer/corefx,ericstj/corefx,Jiayili1/corefx,Jiayili1/corefx,mmitche/corefx,wtgodbe/corefx,ptoonen/corefx,shimingsg/corefx,wtgodbe/corefx,ViktorHofer/corefx,shimingsg/corefx,mmitche/corefx,Jiayili1/corefx,mmitche/corefx,Jiayili1/corefx,ptoonen/corefx,ViktorHofer/corefx,wtgodbe/corefx,wtgodbe/corefx,shimingsg/corefx,shimingsg/corefx,ptoonen/corefx,mmitche/corefx,Jiayili1/corefx,ViktorHofer/corefx