I was looking at this and it its starting comments it says it exists because
throw new ArgumentNullException("key", Environment.GetResourceString("ArgumentNull_Key"));
generates more IL code than
ThrowHelper.ThrowArgumentNullException(ExceptionArgument.key, ExceptionResource.ArgumentNull_Key);
which I can't find in the code, but like its similar methods I assume just calls throw new ArgumentNullException("key", Environment.GetResourceString("ArgumentNull_Key")); or something.
Does the ThrowHelper class really help lessen the IL code generated or is it the same (or more) considering the IL code generated from ThrowHelper.ThrowArgumentNullException(ExceptionArgument.key, ExceptionResource.ArgumentNull_Key);?
EDIT:
The IL shown at the start of the file, in the comments, is only from the call to ThrowHelper.ThrowArgumentNullException(ExceptionArgument.key, ExceptionResource.ArgumentNull_Key); not the actual code inside that method. Or am I wrong?