fix failing test re: Automattic#5078 Automattic#9010

Author: AbdelrahmanHafez

lib/helpers/document/compile.js

@@ -195,6 +195,7 @@ function getOwnPropertyDescriptors(object) {
       return;
     }
     result[key].enumerable = [
+      '$isNew',
       'isNew',
       '$__',
       'errors',

test/document.test.js

@@ -4903,7 +4903,7 @@ describe('document', function() {
       });
 
       schema.virtual('tests').get(function() {
-        return Object.keys(this.nested).map(key => this.nested[key]);
+        return Object.values(this.nested);
       });
 
       const M = db.model('Test', schema);

test/schema.test.js

@@ -1449,11 +1449,6 @@ describe('schema', function() {
         });
       }, /`collection` may not be used as a schema pathname/);
 
-      assert.throws(function() {
-        new Schema({
-          isNew: String
-        });
-      }, /`isNew` may not be used as a schema pathname/);
 
       assert.throws(function() {
         new Schema({
@@ -1466,6 +1461,10 @@ describe('schema', function() {
       new Schema({
         init: String
       });
+
+      new Schema({
+        isNew: String
+      });
     });
 
     it('that do not conflict do not throw', function(done) {