Revert of Simplify form validation handling

Source/core/html/HTMLFormElement.cpp

Index: Source/core/html/HTMLFormElement.cpp
diff --git a/Source/core/html/HTMLFormElement.cpp b/Source/core/html/HTMLFormElement.cpp
index c768e3a45852c1c8356a68f31010e80023e80ef0..bcd39c067668885e6dbdb5253fd757f530fd9ea9 100644
--- a/Source/core/html/HTMLFormElement.cpp
+++ b/Source/core/html/HTMLFormElement.cpp
@@ -78,6 +78,7 @@
     , m_shouldSubmit(false)
     , m_isInResetFunction(false)
     , m_wasDemoted(false)
+    , m_invalidControlsCount(0)
     , m_pendingAutocompleteEventsQueue(GenericEventQueue::create(this))
 {
 }
@@ -713,6 +714,31 @@
     return 0;
 }
 
+void HTMLFormElement::setNeedsValidityCheck(ValidityRecalcReason reason, bool isValid)
+{
+    bool formWasInvalid = m_invalidControlsCount > 0;
+    switch (reason) {
+    case ElementRemoval:
+        if (!isValid)
+            --m_invalidControlsCount;
+        break;
+    case ElementAddition:
+        if (!isValid)
+            ++m_invalidControlsCount;
+        break;
+    case ElementModification:
+        if (isValid)
+            --m_invalidControlsCount;
+        else
+            ++m_invalidControlsCount;
+        break;
+    }
+    if (formWasInvalid && !m_invalidControlsCount)
+        pseudoStateChanged(CSSSelector::PseudoValid);
+    if (!formWasInvalid && m_invalidControlsCount)
+        pseudoStateChanged(CSSSelector::PseudoInvalid);
+}
+
 bool HTMLFormElement::checkValidity()
 {
     return !checkInvalidControlsAndCollectUnhandled(0, CheckValidityDispatchInvalidEvent);
@@ -720,6 +746,9 @@
 
 bool HTMLFormElement::checkInvalidControlsAndCollectUnhandled(WillBeHeapVector<RefPtrWillBeMember<HTMLFormControlElement>>* unhandledInvalidControls, CheckValidityEventBehavior eventBehavior)
 {
+    if (!unhandledInvalidControls && eventBehavior == CheckValidityDispatchNoEvent)
+        return m_invalidControlsCount;
+
     RefPtrWillBeRawPtr<HTMLFormElement> protector(this);
     // Copy associatedElements because event handlers called from
     // HTMLFormControlElement::checkValidity() might change associatedElements.
@@ -732,13 +761,12 @@
     for (unsigned i = 0; i < elements.size(); ++i) {
         if (elements[i]->form() == this && elements[i]->isFormControlElement()) {
             HTMLFormControlElement* control = toHTMLFormControlElement(elements[i].get());
-            if (!control->checkValidity(unhandledInvalidControls, eventBehavior) && control->formOwner() == this) {
+            if (!control->checkValidity(unhandledInvalidControls, eventBehavior) && control->formOwner() == this)
                 ++invalidControlsCount;
-                if (!unhandledInvalidControls && eventBehavior == CheckValidityDispatchNoEvent)
-                    return true;
-            }
-        }
-    }
+        }
+    }
+    if (eventBehavior == CheckValidityDispatchNoEvent)
+        ASSERT(invalidControlsCount == m_invalidControlsCount);
     return invalidControlsCount;
 }