Fixes the following bugs reported with the Silverlight plugin:-...

webkit/glue/plugins/plugin_host.cc

 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "webkit/glue/plugins/plugin_host.h"
 
 #include "base/logging.h"
 #include "base/message_loop.h"
 #include "base/string_util.h"
 #include "webkit/default_plugin/default_plugin_shared.h"
@@ skipping 155 matching lines @@
   // this method, the plug-in recieves a paint message asynchronously.
 
   // The browser redraws invalid areas of the document and any windowless 
   // plug-ins at regularly timed intervals. To force a paint message, the 
   // plug-in can call NPN_ForceRedraw after calling this method.
 
   scoped_refptr<NPAPI::PluginInstance> plugin = FindInstance(id);
   DCHECK(plugin.get() != NULL);
 
   if (plugin.get() && plugin->webplugin()) {
+    if (!plugin->windowless()) {
+      RECT rect = {0};
+      rect.left = invalidRect->left;
+      rect.right = invalidRect->right;
+      rect.top = invalidRect->top;
+      rect.bottom = invalidRect->bottom;
+      ::InvalidateRect(plugin->window_handle(), &rect, FALSE);
+      return;
+    }
+
     if (plugin->throttle_invalidate()) {
       // We need to track plugin invalidates on a per instance basis.
       ThrottledInvalidates plugin_instance_invalidates;
       InstanceThrottledInvalidatesMap::iterator invalidate_index = 
           instance_throttled_invalidates_.find(id);
       if (invalidate_index != instance_throttled_invalidates_.end()) {
         plugin_instance_invalidates = (*invalidate_index).second;
       }
 
       bool throttle_active = 
@@ skipping 658 matching lines @@
                    NPObject* obj,
                    const NPVariant *args,
                    uint32_t argCount,
                    NPVariant *result) {
   NOTREACHED();
   return false;
 }
 
 } // extern "C"