Editor bold button disabled in IE9+

[haysmark]

See:

​http://archive.dojotoolkit.org/nightly/dojotoolkit/dijit/tests/editor/robot/Editor_a11y.html

The first "toolbar navigation" test, "bold", fails. The robot presses shift-tab to navigate to the undo button. When the robot tries to right-arrow to the Bold button, it can't because the rest of the toolbar disabled on the tab press.

You can recreate this manually:

1. Load test_Editor.
2. In the first editor with a toolbar, erase the contents and type "hello".
3. Shift-tab to the editor toolbar.
4. The formatting options become disabled.

Using the IE11 old browser emulation, the button does not disable in IE8 or older. The button also does not disable on other browsers. This sounds a lot like a case of has(ie)<9.

[Douglas Hays]

edchat, can you look into this?

[bill]

Duplicate of #17595.