Instanciate common attributes everywhere so one can simply use the extend method

inlineXHTMLContent.go

@@ -15,7 +15,11 @@ type InlineXHTMLContent struct {
 // newInlineXHTMLContent creates a new InlineXHTMLContent. It returns a
 // *InlineXHTMLContent.
 func newInlineXHTMLContent(mediaType string, div *XHTMLDiv) *InlineXHTMLContent {
-	return &InlineXHTMLContent{Type: mediaType, XHTMLDiv: div}
+	return &InlineXHTMLContent{
+		CommonAttributes: newCommonAttributes(),
+		Type:             mediaType,
+		XHTMLDiv:         div,
+	}
 }
 
 // isContent checks whether the InlineXHTMLContent is a Content. It returns a