Include polyfills (to be served on promisejs.org)

The polyfills are for browser use, so do not include node.js extensions,
but do include a minimal implementation of `Promise.prototype.done` as I
believe that it is a feature that will be needed in browsers for the
forseable future, and will hopefully eventually make it into the spec.

Author: Forbes Lindesay

polyfill-done.js

@@ -0,0 +1,12 @@
+// should work in any browser without browserify
+
+if (typeof Promise.prototype.done !== 'function') {
+  Promise.prototype.done = function (onFulfilled, onRejected) {
+    var self = arguments.length ? this.then.apply(this, arguments) : this
+    self.then(null, function (err) {
+      setTimeout(function () {
+        throw err
+      }, 0)
+    })
+  }
+}

polyfill.js

@@ -0,0 +1,10 @@
+// not "use strict" so we can declare global "Promise"
+
+var asap = require('asap');
+
+if (typeof Promise === 'undefined') {
+  Promise = require('./lib/core.js')
+  require('./lib/es6-extensions.js')
+}
+
+require('./polfill-done.js');