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

webkit/glue/plugins/plugin_host.cc

Index: webkit/glue/plugins/plugin_host.cc
===================================================================
--- webkit/glue/plugins/plugin_host.cc	(revision 1706)
+++ webkit/glue/plugins/plugin_host.cc	(working copy)
@@ -173,6 +173,16 @@
   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;