LibWeb: Implement validation_message for form associated elements

It wins us a quick WPT test as well as implement a bunch of IDL methods.

Libraries/LibWeb/HTML/FormAssociatedElement.cpp

@@ -259,6 +259,24 @@ bool FormAssociatedElement::will_validate() const
     return is_candidate_for_constraint_validation();
 }
 
+// https://html.spec.whatwg.org/multipage/form-control-infrastructure.html#dom-cva-validationmessage
+Utf16String FormAssociatedElement::validation_message() const
+{
+    // 1. If this element is not a candidate for constraint validation or if this element satisfies its constraints,
+    //    then return the empty string.
+    if (!is_candidate_for_constraint_validation() || satisfies_its_constraints())
+        return {};
+
+    // FIXME
+    // 2. Return a suitably localized message that the user agent would show the user if this were the only form
+    //    control with a validity constraint problem. If the user agent would not actually show a textual message in
+    //    such a situation (e.g., it would show a graphical cue instead), then return a suitably localized message that
+    //    expresses (one or more of) the validity constraint(s) that the control does not satisfy. If the element is a
+    //    candidate for constraint validation and is suffering from a custom error, then the custom validity error
+    //    message should be present in the return value.
+    return "Invalid form"_utf16;
+}
+
 // https://html.spec.whatwg.org/multipage/form-control-infrastructure.html#check-validity-steps
 bool FormAssociatedElement::check_validity_steps()
 {

Libraries/LibWeb/HTML/FormAssociatedElement.h

@@ -149,6 +149,9 @@ public:
     // https://html.spec.whatwg.org/multipage/form-control-infrastructure.html#dom-cva-willvalidate
     bool will_validate() const;
 
+    // https://html.spec.whatwg.org/multipage/form-control-infrastructure.html#dom-cva-validationmessage
+    Utf16String validation_message() const;
+
     // https://html.spec.whatwg.org/multipage/form-control-infrastructure.html#dom-cva-validity
     GC::Ref<ValidityState const> validity() const;
 

Libraries/LibWeb/HTML/HTMLButtonElement.idl

@@ -30,7 +30,7 @@ interface HTMLButtonElement : HTMLElement {
 
     readonly attribute boolean willValidate;
     readonly attribute ValidityState validity;
-    [FIXME] readonly attribute DOMString validationMessage;
+    readonly attribute Utf16DOMString validationMessage;
     boolean checkValidity();
     boolean reportValidity();
     undefined setCustomValidity(DOMString error);

Libraries/LibWeb/HTML/HTMLFieldSetElement.idl

@@ -16,7 +16,7 @@ interface HTMLFieldSetElement : HTMLElement {
 
     readonly attribute boolean willValidate;
     [FIXME, SameObject] readonly attribute ValidityState validity;
-    [FIXME] readonly attribute DOMString validationMessage;
+    readonly attribute Utf16DOMString validationMessage;
     boolean checkValidity();
     boolean reportValidity();
     undefined setCustomValidity(DOMString error);

Libraries/LibWeb/HTML/HTMLInputElement.idl

@@ -54,7 +54,7 @@ interface HTMLInputElement : HTMLElement {
 
     readonly attribute boolean willValidate;
     readonly attribute ValidityState validity;
-    [FIXME] readonly attribute DOMString validationMessage;
+    readonly attribute Utf16DOMString validationMessage;
     boolean checkValidity();
     boolean reportValidity();
     undefined setCustomValidity(DOMString error);

Libraries/LibWeb/HTML/HTMLObjectElement.idl

@@ -20,7 +20,7 @@ interface HTMLObjectElement : HTMLElement {
 
     readonly attribute boolean willValidate;
     readonly attribute ValidityState validity;
-    [FIXME] readonly attribute DOMString validationMessage;
+    readonly attribute Utf16DOMString validationMessage;
     boolean checkValidity();
     boolean reportValidity();
     undefined setCustomValidity(DOMString error);

Libraries/LibWeb/HTML/HTMLOutputElement.idl

@@ -17,7 +17,7 @@ interface HTMLOutputElement : HTMLElement {
 
     readonly attribute boolean willValidate;
     readonly attribute ValidityState validity;
-    [FIXME] readonly attribute DOMString validationMessage;
+    readonly attribute Utf16DOMString validationMessage;
     boolean checkValidity();
     boolean reportValidity();
     undefined setCustomValidity(DOMString error);

Libraries/LibWeb/HTML/HTMLSelectElement.idl

@@ -33,7 +33,7 @@ interface HTMLSelectElement : HTMLElement {
 
     readonly attribute boolean willValidate;
     readonly attribute ValidityState validity;
-    [FIXME] readonly attribute DOMString validationMessage;
+    readonly attribute Utf16DOMString validationMessage;
     boolean checkValidity();
     boolean reportValidity();
     undefined setCustomValidity(DOMString error);

Libraries/LibWeb/HTML/HTMLTextAreaElement.idl

@@ -28,7 +28,7 @@ interface HTMLTextAreaElement : HTMLElement {
 
     readonly attribute boolean willValidate;
     readonly attribute ValidityState validity;
-    [FIXME] readonly attribute DOMString validationMessage;
+    readonly attribute Utf16DOMString validationMessage;
     boolean checkValidity();
     boolean reportValidity();
     undefined setCustomValidity(DOMString error);

Tests/LibWeb/Text/expected/wpt-import/html/semantics/forms/constraints/form-validation-validity-valueMissing.txt

@@ -2,8 +2,7 @@ Harness status: OK
 
 Found 78 tests
 
-77 Pass
+78 Pass
-1 Fail
 Pass	[INPUT in TEXT status] The required attribute is not set
 Pass	[INPUT in TEXT status] The value is not empty and required is true
 Pass	[INPUT in TEXT status] The value is empty and required is true
@@ -81,4 +80,4 @@ Pass	[select]  Selected the option with value equals to empty
 Pass	[textarea]  The required attribute is not set
 Pass	[textarea]  The value is not empty
 Pass	[textarea]  The value is empty
-Fail	validationMessage should return empty string when willValidate is false and valueMissing is true
+Pass	validationMessage should return empty string when willValidate is false and valueMissing is true