[expr.ref] Do not say that the direct base relationship is (T1, B)

Author: cpplearner

source/expressions.tex

@@ -4258,7 +4258,7 @@
 then let \tcode{T1} be the type of \tcode{E1}.
 \tcode{E2} shall designate either
 a member of \tcode{T1} or
-a direct base class relationship $(\tcode{T1}, \tcode{B})$.
+a direct base class relationship.
 
 \pnum
 If \tcode{E2} designates a bit-field, \tcode{E1.E2} is a bit-field. The