Promises (first look)

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Small fixes

vendors/Q/design/q4.js

@@ -0,0 +1,48 @@
+
+var isPromise = function (value) {
+    return value && typeof value.then === "function";
+};
+
+var defer = function () {
+    var pending = [], value;
+    return {
+        resolve: function (_value) {
+            if (pending) {
+                value = ref(_value); // values wrapped in a promise
+                for (var i = 0, ii = pending.length; i < ii; i++) {
+                    var callback = pending[i];
+                    value.then(callback); // then called instead
+                }
+                pending = undefined;
+            }
+        },
+        promise: {
+            then: function (_callback) {
+                var result = defer();
+                // callback is wrapped so that its return
+                // value is captured and used to resolve the promise
+                // that "then" returns
+                var callback = function (value) {
+                    result.resolve(_callback(value));
+                };
+                if (pending) {
+                    pending.push(callback);
+                } else {
+                    value.then(callback);
+                }
+                return result.promise;
+            }
+        }
+    };
+};
+
+var ref = function (value) {
+    if (value && typeof value.then === "function")
+        return value;
+    return {
+        then: function (callback) {
+            return ref(callback(value));
+        }
+    };
+};
+