Compare numbers to detect modified

Depending on the language settings, the input number may remove the trailing 0
(ex: fr). So we must compare the Number instances by stringify them.

issue9340
review307611002

src/view/form.js

@@ -1795,7 +1795,8 @@ function eval_pyson(value){
         get modified() {
             if (this.record && this.field) {
                 var value = this.get_client_value();
-                return value != this.get_value();
+                return (JSON.stringify(this.field.convert(value)) !=
+                    JSON.stringify(this.field.convert(this.get_value())));
             }
             return false;
         },