accounts/abi: add support for "anonymous" and "indexed" for events (#3464)

accounts/abi/argument.go

@@ -33,6 +33,7 @@ func (a *Argument) UnmarshalJSON(data []byte) error {
 	var extarg struct {
 		Name string
 		Type string
+		Indexed bool
 	}
 	err := json.Unmarshal(data, &extarg)
 	if err != nil {
@@ -44,6 +45,7 @@ func (a *Argument) UnmarshalJSON(data []byte) error {
 		return err
 	}
 	a.Name = extarg.Name
+	a.Indexed = extarg.Indexed
 
 	return nil
 }