Revert^2 "Derive synthetic type bounds for expressions""

Reverts https://codereview.chromium.org/17842004 (again), due to SS regression.

R=jkummerow@chromium.org
BUG=

Review URL: https://codereview.chromium.org/18337003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15559 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/objects.cc

@@ -15850,7 +15850,7 @@ MaybeObject* PropertyCell::SetValueInferType(Object* value,
         &PropertyCell::UpdateType,
         Handle<PropertyCell>(this),
         Handle<Object>(value, GetIsolate()));
-    Type* new_type = NULL;
+    Type* new_type;
     if (maybe_type->To(&new_type)) return maybe_type;
     set_type(new_type);
   }

src/typing.h

@@ -68,12 +68,6 @@ class AstTyper: public AstVisitor {
   void MergeUpperType(Expression* e, Handle<Type> t) {
     e->set_upper_type(handle(Type::Intersect(e->upper_type(), t), isolate_));
   }
-  void MergeLowerType(Expression* e, Type* t) {
-    MergeLowerType(e, handle(t, isolate_));
-  }
-  void MergeUpperType(Expression* e, Type* t) {
-    MergeUpperType(e, handle(t, isolate_));
-  }
 
   void VisitDeclarations(ZoneList<Declaration*>* declarations);
   void VisitStatements(ZoneList<Statement*>* statements);