No children of TabContainer/AccordionContainer should have a border, since the parent TabContainer/AccordionContainer supplies a border on it's containerNode.   Generalize the no-border rules and move them to dijit.css.
No children of TabContainer/AccordionContainer should have a border, since the parent TabContainer/AccordionContainer supplies a border on it's containerNode.   Generalize the no-border rules and move them to dijit.css.

There's still a glitch when the *child* is an AccordionContainer b/c it's top border comes from a sub-node, not the main DOM node.

Refs #6437.

git-svn-id: 674a2d6b1e32e53f607eb824547723f32280967e@16074 560b804f-0ae3-0310-86f3-f6aa0a117693

Sam-Cummins/delite,Sam-Cummins/delite,harbalk/delite,harbalk/delite,kitsonk/delite,kitsonk/delite