Deferred: produce and consume standard thenables

Deferred.then is now aligned with the emerging standard. Objects that implement
the thenable interface will also be properly consumed.

We use Q to test interoperability.

Fixes #14510

Author: jaubourg

Gruntfile.js

@@ -55,6 +55,9 @@ module.exports = function( grunt ) {
 					"sizzle/dist": "sizzle/dist",
 					"sizzle/LICENSE.txt": "sizzle/LICENSE.txt",
 
+					"q/q.js": "q/q.js",
+					"q/LICENSE.txt": "q/LICENSE",
+
 					"qunit/qunit.js": "qunitjs/qunit/qunit.js",
 					"qunit/qunit.css": "qunitjs/qunit/qunit.css",
 					"qunit/MIT-LICENSE.txt": "qunitjs/MIT-LICENSE.txt",

external/q/LICENSE.txt

@@ -0,0 +1,18 @@
+Copyright 2009–2014 Kristopher Michael Kowal. All rights reserved.
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to
+deal in the Software without restriction, including without limitation the
+rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+sell copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+IN THE SOFTWARE.