convert Tree robot tests to AMD, refs #14279

git-svn-id: http://svn.dojotoolkit.org/src/dijit/trunk@31438 560b804f-0ae3-0310-86f3-f6aa0a117693
(cherry picked from commit 75df1cd0380274e22c49e38f6775bfdd5cad45cb)
fixes #17207: fix Tree openOnDblClick regression

cherry picked from commits:
  - b051fc9586224f2ce67c0f37966a0971052df627
  - 75cf90f06b81c096c36de1a8a9a42838c53d23ed
  - af7db126555b5c6179f00e2bcac7b271c0fde215