[turbofan] Drop obsolete unused JSStrictNotEqual operator.

src/compiler/typer.cc

Index: src/compiler/typer.cc
diff --git a/src/compiler/typer.cc b/src/compiler/typer.cc
index 82572927bb363855ba081f2aefb9c7b253a840d3..f1a3a807fa4dad2700db1ab74bdc5041aaf9991d 100644
--- a/src/compiler/typer.cc
+++ b/src/compiler/typer.cc
@@ -931,11 +931,6 @@ Type* Typer::Visitor::JSStrictEqualTyper(Type* lhs, Type* rhs, Typer* t) {
 }
 
 
-Type* Typer::Visitor::JSStrictNotEqualTyper(Type* lhs, Type* rhs, Typer* t) {
-  return Invert(JSStrictEqualTyper(lhs, rhs, t), t);
-}
-
-
 // The EcmaScript specification defines the four relational comparison operators
 // (<, <=, >=, >) with the help of a single abstract one.  It behaves like <
 // but returns undefined when the inputs cannot be compared.