Empty dir="" and lang="" attributes on tree and tabcontainer elements causes accessibility violations

[bill]

If we do not explicitly set a lang or dir for Tree and TabContainer widgets, dijit is incorrectly adding dir and lang empty attributes.

This is an example from a TabContainer, and dir is set correctly, but lang="" is invalid DOM:

<div id="verifyHostContainer_ tablist" class="dijitTabListContainer- top tabStrip-disabled" lang="" styl e="visibility: visible;" dir="ltr" widgetid="v erifyHostContainer_tablist" role="ta blist">
<div class="tabStripButton- top dijitTab tabStripButton" lang="" dojoatt achevent="onclick:_onButtonClick" di r="ltr" widgetid="verifyHostContainer_ tablist_menuBtn" _dijitmenuverifyhostcontainer_ tablist_menu="1">
</div>
& lt;div class="tabStripButton-top dijitTab tabStripButton" lang="" dojoatt achevent="onclick:_onButtonClick" di r="ltr" widgetid="verifyHostContainer_ tablist_leftBtn">
</div>
& lt;div class="tabStripButton-top dijitTab tabStripButton" lang="" dojoatt achevent="onclick:_onButtonClick" di r="ltr" widgetid="verifyHostContainer_ tablist_rightBtn">
</div>
<div class="dijitTabListWrapper dijitTabContainerTopNone" dojoattach point="tablistWrapper">

This is an example from a tree where both lang and dir are empty and causing violations:

div class="dijitTreeC ontainer" style="height: auto;" wairole="presentation" d ojoattachpoint="containerNode" role= "group">
<div id="dijit__TreeNode_ 1" class="dijitTreeNode dijitTreeNodeUNCHECKED dijitUNCHECKED dijitTreeIsRoot" lang="" wairol e="presentation" role="presentation"  dir="" style="background-posit ion: 0px 0px;" widgetid="dijit__TreeNode_1">
</ div>
<div id="dijit__TreeNode_ 9" class="dijitTreeNode dijitTreeNodeUNCHECKED dijitUNCHECKED dijitTreeIsRoot" lang="" wairol e="presentation" role="presentation"  dir="" style="background-posit ion: 0px 0px;" widgetid="dijit__TreeNode_9">
</ div>
<div id="dijit__TreeNode_ 16" class="dijitTreeNode dijitTreeNodeUNCHECKED dijitUNCHECKED dijitTreeIsRoot" lang="" wairol e="presentation" role="presentation"  dir="" style="background-posit ion: 0px 0px;" widgetid="dijit__TreeNode_16"& gt;

[bill]

(In [25944]) Don't put empty dir="" and lang="" on internal widgets such as TreeNode. Fixes #13543 !strict.