html form validation initial steps with test html file, added stub methods, added code to handle validations

components/script/dom/validation.rs

@@ -1,5 +1,9 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+use dom::validitystate::ValidationFlags;
 
-pub trait Validatable {}
+pub trait Validatable {
+    fn is_instance_validatable(&self) -> bool { true }
+    fn validate(&self, _validate_flags: ValidationFlags) -> bool { true }
+}