Replace code generated SVG triangle above dialog inline messages with CSS solution

For the small triangle above inline messages in dialogs and older Vaadin add-on, GWT-Graphics, is used to generate it. The library uses SVG if available or VML as Fallback. Internet Explorer 9 supported SVG for the first time and in the Version 10 the VML support was removed.

The library has issues with Internet Explorer 10 and above because it doesn't seem to recognise them and use the fallback (VML) which is not supported.

The gwt-graphics code in InlineMessageWidget for creating the svg triangle has to be removed and replaced with CSS solution. The workaround from MGNLUI-3289 in CommonWidgetSet.gwt.xml should be removed as well.