Canonicalize away simple arithmetic equivalences.

runtime/vm/intermediate_language.h

Index: runtime/vm/intermediate_language.h
diff --git a/runtime/vm/intermediate_language.h b/runtime/vm/intermediate_language.h
index b8ac5a3f0dce352d193dc6eba9c9dc24820abbb6..ec6a7b579695377e322574b6eb2e57522234c6ac 100644
--- a/runtime/vm/intermediate_language.h
+++ b/runtime/vm/intermediate_language.h
@@ -3624,6 +3624,8 @@ class BinaryDoubleOpInstr : public TemplateDefinition<2> {
   DECLARE_INSTRUCTION(BinaryDoubleOp)
   virtual RawAbstractType* CompileType() const;
 
+  virtual Definition* Canonicalize(FlowGraphOptimizer* optimizer);
+
  private:
   const Token::Kind op_kind_;
 
@@ -3853,6 +3855,8 @@ class BinarySmiOpInstr : public TemplateDefinition<2> {
 
   virtual void InferRange();
 
+  virtual Definition* Canonicalize(FlowGraphOptimizer* optimizer);
+
  private:
   const Token::Kind op_kind_;
   InstanceCallInstr* instance_call_;