dojo.attr() doesn't handle style or innerHTML values well

[alex]

Passing styles into dojo.attr() should be easier. e.g.:

dojo.attr("nodeId", {
  tabIndex: "-1",
  style: {
    opacity: 0.5,
    border: "5px dotted blue"
  }
});

Doesn't currently work as you'd expect. Obviously, style is a special case here, but one which we should handle.

Likewise, specifying content is too hard. This should be possible:

dojo.attr("nodeId", {
  tabIndex: "-1",
  innerHTML: "howdy!"
});

[alex]

(In [14608]) update dojo.attr() to handle the case of innerHTML and style: {...} being passed in as values. Fixes #7305. !strict