Auto merge of #13969 - bbansalWolfPack:master, r=jdm

html form validation initial steps with  test html file

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Added code for initial steps in html form validation.
1. Added methods for trait validatable
2. implemented stub methods for  elements like HTMLInputElement, HTMLButtonElement, etc

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- [ X] `./mach test-tidy` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).

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- [ ] There are tests for these changes OR
- [ ] These changes do not require tests because _____

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components/script/dom/htmlselectelement.rs

@@ -28,7 +28,7 @@ use dom::htmloptionscollection::HTMLOptionsCollection;
 use dom::node::{Node, UnbindContext, window_from_node};
 use dom::nodelist::NodeList;
 use dom::validation::Validatable;
-use dom::validitystate::ValidityState;
+use dom::validitystate::{ValidityState, ValidationFlags};
 use dom::virtualmethods::VirtualMethods;
 use html5ever_atoms::LocalName;
 use style::attr::AttrValue;
@@ -384,4 +384,13 @@ impl VirtualMethods for HTMLSelectElement {
 
 impl FormControl for HTMLSelectElement {}
 
-impl Validatable for HTMLSelectElement {}
+impl Validatable for HTMLSelectElement {
+    fn is_instance_validatable(&self) -> bool {
+        true
+    }
+    fn validate(&self, validate_flags: ValidationFlags) -> bool {
+        if validate_flags.is_empty() {}
+        // Need more flag check for different validation types later
+        true
+    }
+}