Narrow result cid and type of BinarySmiOp to be always smi.

runtime/vm/intermediate_language.cc

Index: runtime/vm/intermediate_language.cc
===================================================================
--- runtime/vm/intermediate_language.cc	(revision 16037)
+++ runtime/vm/intermediate_language.cc	(working copy)
@@ -1323,12 +1323,12 @@
 
 
 RawAbstractType* BinarySmiOpInstr::CompileType() const {
-  return (op_kind() == Token::kSHL) ? Type::IntType() : Type::SmiType();
+  return Type::SmiType();
 }
 
 
 intptr_t BinarySmiOpInstr::ResultCid() const {
-  return (op_kind() == Token::kSHL) ? kDynamicCid : kSmiCid;
+  return kSmiCid;
 }