Add aria-labelledby for TreeNode.containerNode, fixes #17705.

Also update test_Tree.html to use aria-labelledby rather than aria-label;
there's no reason to list a tree's label twice.
add textarea to list of elements to allow click native behavior, refs #17816.
Destroyable should forget Promises that are resolved or rejected, refs #17680.
modernize test, refs #9575
fix typo, refs #17680
ObjectStoreModel fixes for asynchronous stores.
Added async tests to Tree_ObjectStoreModel.html, and lots of cleanup too.

Refs #17836, fixes #17837.
make ObjectStoreModel leverage Destroyable, refs #17837
fix typo from 302c1fe542b646a07dfce94172e4a61345768354, refs #17837.
remove completed TODO comment, it's handled by _isParentChildDrop(), refs #7140
Disallow drop onto own parent
unless user is dragging multiple nodes and at least
one of them is *not* being dropped onto its own parent.

In that case, no-op for node(s) being dropped onto their own parent.

Fixes #16692
Add TODO, refs #8306
Prevent placeholder from wrapping, fixes #17881.
Tried text-overflow:ellipsis too but it didn't work for some reason.
reset focus when Tree's focused node is destroyed, fixes #6236
use AMD dojo/_base/window module to reach body() fct
Hide Tooltip when ValidationTextBox or Select widget destroyed.
Partially fixes #17366, and the other part is wontfix.
Pass oldParent to store.put() too, fixes #17902.
No infrastructure for testing this though, unfortunately.
The Tree_DnD_multiParent.html test is still running against dojo/data.
refactor TextColor plugin to allow custom ColorPicker, fixes #16908
Fix ComboButton click on webkit mobile (iOS and android).
Set dijitOffScreen class on <input> so dojo/touch doesn't squelch the
click event generated from _ButtonMixin's call to this.valueNode.click().

Fixes #17693.
fix test typo and update source code comment, refs #17693
Widgets that use ondijitclick in their templates should list dijit/a11yclick
as a dependency.  Refs #17693 tangentially.