Implement :valid and :invalid pseudoclass for <form>

Source/core/html/HTMLFormControlElement.cpp

Index: Source/core/html/HTMLFormControlElement.cpp
diff --git a/Source/core/html/HTMLFormControlElement.cpp b/Source/core/html/HTMLFormControlElement.cpp
index 6029f3fe1e814339a8d896db5eb0e1bf69de265b..a6a97915f684137cea3bfd027c219301b5628a40 100644
--- a/Source/core/html/HTMLFormControlElement.cpp
+++ b/Source/core/html/HTMLFormControlElement.cpp
@@ -246,6 +246,13 @@ void HTMLFormControlElement::didMoveToNewDocument(Document& oldDocument)
     HTMLElement::didMoveToNewDocument(oldDocument);
 }
 
+void HTMLFormControlElement::setFormOwnerNeedsStyleRecalc()

[keishi, 2014/10/03 03:44:13]

I think this should be done by the HTMLFormElement in a method like
HTMLFormElement::setNeedsValidityCheck(). We have some exceptions but I think
elements should decide if it needs style recalc for itself not for other
elements. For example in this case, if you implement caching HTMLFormElement
could tell when the validity hasn't changed and avoid a style recalc.

[Bartek Nowierski, 2014/10/03 06:01:33]

Done.

+{
+    HTMLFormElement* form = formOwner();
+    if (form)
+        form->setNeedsStyleRecalc(SubtreeStyleChange, StyleChangeReasonForTracing::createWithExtraData(StyleChangeReason::PseudoClass, StyleChangeExtraData::Invalid));
+}
+
 Node::InsertionNotificationRequest HTMLFormControlElement::insertedInto(ContainerNode* insertionPoint)
 {
     m_ancestorDisabledState = AncestorDisabledStateUnknown;
@@ -253,11 +260,22 @@ Node::InsertionNotificationRequest HTMLFormControlElement::insertedInto(Containe
     setNeedsWillValidateCheck();
     HTMLElement::insertedInto(insertionPoint);
     FormAssociatedElement::insertedInto(insertionPoint);
+
+    // Element addition can change validity of the form.

[keishi, 2014/10/03 03:44:13]

I think you'll find that Blink is light on comments. People often complain about
it, but it is a tradition carried over from WebKit. It is so we try to make the
code describe what we are doing so we don't need comments.

If we use HTMLFormElement::setNeedsValidityCheck() here, I think it will be more
clear that we are expecting  a validity change on the form and we won't need
this comment.

[Bartek Nowierski, 2014/10/03 06:01:33]

Done.

+    // Order form style recalculation (do it at the end to ensure that form
+    // owner is set).
+    setFormOwnerNeedsStyleRecalc();
+
     return InsertionDone;
 }
 
 void HTMLFormControlElement::removedFrom(ContainerNode* insertionPoint)
 {
+    // Element removal can definitely change validity of the form.
+    // Order form style recalculation (do it at the begining to ensure that
+    // form owner is still set).
+    setFormOwnerNeedsStyleRecalc();
+
     hideVisibleValidationMessage();
     m_hasValidationMessage = false;
     m_ancestorDisabledState = AncestorDisabledStateUnknown;
@@ -469,7 +487,7 @@ ValidationMessageClient* HTMLFormControlElement::validationMessageClient() const
 
 bool HTMLFormControlElement::checkValidity(WillBeHeapVector<RefPtrWillBeMember<FormAssociatedElement> >* unhandledInvalidControls)
 {
-    if (!willValidate() || isValidFormControlElement())
+    if (!willValidate() || isValidElement())
         return true;
     // An event handler can deref this object.
     RefPtrWillBeRawPtr<HTMLFormControlElement> protector(this);
@@ -480,7 +498,7 @@ bool HTMLFormControlElement::checkValidity(WillBeHeapVector<RefPtrWillBeMember<F
     return false;
 }
 
-bool HTMLFormControlElement::isValidFormControlElement()
+bool HTMLFormControlElement::isValidElement()
 {
     // If the following assertion fails, setNeedsValidityCheck() is not called
     // correctly when something which changes validity is updated.
@@ -493,6 +511,11 @@ void HTMLFormControlElement::setNeedsValidityCheck()
     bool newIsValid = valid();
     if (willValidate() && newIsValid != m_isValid) {
         // Update style for pseudo classes such as :valid :invalid.
+        // A change here could've affected the style of the form itself and
+        // other form elemetns, so recaluclate the entire form's subtree.
+        setFormOwnerNeedsStyleRecalc();
+        // Then recalculate the element itself (and its subtree), because
+        // it might not be in the tree of the owner form.
         setNeedsStyleRecalc(SubtreeStyleChange, StyleChangeReasonForTracing::createWithExtraData(StyleChangeReason::PseudoClass, StyleChangeExtraData::Invalid));
     }
     m_isValid = newIsValid;