[turbofan] Fix overly aggressive dead code elimination.

src/compiler/typer.cc

Index: src/compiler/typer.cc
diff --git a/src/compiler/typer.cc b/src/compiler/typer.cc
index af1eded27cc87eff3f60b3c48ed8fba36cd59c65..98cf98ac337a6a1325452742970fc56eba1d3906 100644
--- a/src/compiler/typer.cc
+++ b/src/compiler/typer.cc
@@ -810,9 +810,7 @@ Type* Typer::Visitor::TypeProjection(Node* node) {
   return Type::Any();
 }
 
-
-Type* Typer::Visitor::TypeDead(Node* node) { return Type::Any(); }
-
+Type* Typer::Visitor::TypeDead(Node* node) { return Type::None(); }
 
 // JS comparison operators.