Add frameborder="0" on iframe elements for IE<=8

plugins/help/skins/larry/templates/help.html

@@ -19,7 +19,7 @@
 
 <div id="pluginbody" class="uibox offset">
 	<div class="iframebox help_<roundcube:var name='env:action' />">
-		<roundcube:object name="helpcontent" id="helpcontentframe" style="width:100%; height:100%" src="/watermark.html" />
+		<roundcube:object name="helpcontent" id="helpcontentframe" style="width:100%; height:100%" frameborder="0" src="/watermark.html" />
 	</div>
 	<roundcube:object name="message" id="message" class="statusbar" />
 </div>