EXT-6994 FIXED Enabled context menu for expandable text control.

reviewed by Mike Antipov at https://codereview.productengine.com/secondlife/r/387/

--HG--
branch : product-engine

indra/newview/skins/default/xui/en/widgets/expandable_text.xml

@@ -11,6 +11,7 @@
   read_only="true"
   use_ellipses="true"
   word_wrap="true"
+  show_context_menu="true"
   tab_stop="true"
   v_pad="3"
   h_pad="4" >