Reviewed by Adam Barth.

        Add checks if setNeedsWillValidateCheck() and
        setNeedsValidityCheck() are called correctly.
        https://bugs.webkit.org/show_bug.cgi?id=34924

        Introduce HTMLFormControlElement::m_willValidate and
        m_isValid. They are the caches of willValidate() and
        isValidFormControlElement(). setNeedsWillValidateCheck() updates
        m_willValidate and setNeedsValidityCheck() updates m_isValid.

        willValidate() and isValidFormControlElement() have assertions to
        check m_willvalidate or m_isValid has the correct state. If
        setNeedsWillValidateCheck() or setNeedsValidityCheck() is needed
        to be called and is not called, these assertions fail.

        * html/HTMLButtonElement.h:
        (WebCore::HTMLButtonElement::recalcWillValidate):
        * html/HTMLFieldSetElement.h:
        (WebCore::HTMLFieldSetElement::recalcWillValidate):
        * html/HTMLFormControlElement.cpp:
        (WebCore::HTMLFormControlElement::HTMLFormControlElement):
        (WebCore::HTMLFormControlElement::parseMappedAttribute):
        (WebCore::HTMLFormControlElement::recalcWillValidate):
        (WebCore::HTMLFormControlElement::willValidate):
        (WebCore::HTMLFormControlElement::setNeedsWillValidateCheck):
        (WebCore::HTMLFormControlElement::validationMessage):
        (WebCore::HTMLFormControlElement::isValidFormControlElement):
        (WebCore::HTMLFormControlElement::setNeedsValidityCheck):
        * html/HTMLFormControlElement.h:
        * html/HTMLInputElement.cpp:
        (WebCore::HTMLInputElement::setInputType):
        (WebCore::HTMLInputElement::parseMappedAttribute):
        (WebCore::HTMLInputElement::setValue):
        (WebCore::HTMLInputElement::recalcWillValidate):
        * html/HTMLInputElement.h:
        * html/HTMLTextAreaElement.cpp:
        (WebCore::HTMLTextAreaElement::setNonDirtyValue):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@56385 268f45cc-cd09-0410-ab3c-d52691b4dbfc