[patch/cla] Tooltip content inacessible by CSS

[dante]

I encountered a use case of wanting to be able to display Tooltip content when a user prints a page. Typically the way to do this

@media print { /* do something } 

but the Tooltip data is set display:none by postCreate, and no additional CSS-based access to the node (other than by ID, but that's cumbersome) can be made. Attached patch removes JS styling of the srcNode, adding a class "dijitTooltipData" to the domNode. this makes something like:

@media print {
    .dijitTooltipData {
       display:block;
       border:2px solid red; 
    }
} 

work.

[dante]

my patch

[dante]

(In [13410]) fixes #6596 - add the ability to access Tooltip srcNode's via standard css. partially refs #6597, which will come in as several checkins pending full testing for each widget modified. iirc, this patch received explict, though hesitant, approval.