Reviewed by Adele.

    Reviewed by Adele.

        Improve popup menu behavior.

        * html/HTMLSelectElement.cpp:
        (WebCore::HTMLSelectElement::HTMLSelectElement): Cache
        m_lastOnChangeIndex so we know when to fire onChange.
        (WebCore::HTMLSelectElement::setSelectedIndex): Added parameter to
        specify whether we should fire onChange.
        (WebCore::HTMLSelectElement::dispatchBlurEvent): Fire onChange on blur.
        (WebCore::HTMLSelectElement::menuListDefaultEventHandler): Fire
        onChange when using the Enter key to change the selection.
        * html/HTMLSelectElement.h:
        * rendering/RenderMenuList.cpp:
        (WebCore::RenderMenuList::updateFromElement): Extract setText logic
        into its own method.
        (WebCore::RenderMenuList::setTextFromOption): New method.
        (WebCore::RenderMenuList::valueChanged): Let setSelectedIndex call
        onChange instead of calling it directly here.
        * rendering/RenderMenuList.h:

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@16977 268f45cc-cd09-0410-ab3c-d52691b4dbfc