Use AST's type field and merge types for unary, binary & compare ICs

src/typing.h

Index: src/typing.h
diff --git a/src/typing.h b/src/typing.h
index 1f172eaf59b6f59100e4f92f485b35bc4a02f5ee..2d3fac0650959cb9f6ac719b3973456510702b69 100644
--- a/src/typing.h
+++ b/src/typing.h
@@ -62,6 +62,13 @@ class AstTyper: public AstVisitor {
   TypeFeedbackOracle* oracle() { return &oracle_; }
   Zone* zone() const { return info_->zone(); }
 
+  void MergeLowerType(Expression* e, Handle<Type> t) {
+    e->set_lower_type(handle(Type::Union(e->lower_type(), t), isolate_));
+  }
+  void MergeUpperType(Expression* e, Handle<Type> t) {
+    e->set_upper_type(handle(Type::Intersect(e->upper_type(), t), isolate_));
+  }
+
   void VisitDeclarations(ZoneList<Declaration*>* declarations);
   void VisitStatements(ZoneList<Statement*>* statements);