Reviewed by Sam Weinig.

        Implement using plug-in objects as constructors, and setting and getting properties from a plug-in object.
        
        * Plugins/Hosted/NetscapePluginHostProxy.mm:
        (WKPCBooleanAndDataReply):
        * Plugins/Hosted/NetscapePluginInstanceProxy.h:
        (WebKit::NetscapePluginInstanceProxy::Reply::):
        (WebKit::NetscapePluginInstanceProxy::BooleanAndDataReply::BooleanAndDataReply):
        Rename NPObjectInvokeReply to BooleanAndDataReply.
        
        * Plugins/Hosted/NetscapePluginInstanceProxy.mm:
        (WebKit::NetscapePluginInstanceProxy::addValueToArray):
        Fix a cut and paste error.
        
        (WebKit::NetscapePluginInstanceProxy::demarshalValueFromArray):
        Handle NPObjects.
        
        * Plugins/Hosted/ProxyInstance.h:
        * Plugins/Hosted/ProxyInstance.mm:
        (WebKit::ProxyField::valueFromInstance):
        (WebKit::ProxyField::setValueToInstance):
        Call the ProxyInstance method.
        
        (WebKit::ProxyInstance::~ProxyInstance):
        Release the NPObject.
        
        (WebKit::ProxyInstance::supportsConstruct):
        Ask the plug-in host if an instance supports construct.
        
        (WebKit::ProxyInstance::fieldValue):
        (WebKit::ProxyInstance::setFieldValue):
        Call the plug-in host methods.
        
        * Plugins/Hosted/WebKitPluginHostTypes.h:
        Rename ObjectValueType to JSObjectValueType, and add NPObjectValueType.



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@40263 268f45cc-cd09-0410-ab3c-d52691b4dbfc