Unrevert "Derive synthetic type bounds for expressions"

Reenables https://codereview.chromium.org/17842004

R=jkummerow@chromium.org
BUG=

Review URL: https://codereview.chromium.org/18847002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15552 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;
+    Type* new_type = NULL;
     if (maybe_type->To(&new_type)) return maybe_type;
     set_type(new_type);
   }

src/typing.h

@@ -68,6 +68,12 @@ 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);