Promises (first look)

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Small fixes

vendors/Q/design/q7.js

@@ -0,0 +1,126 @@
+
+var enqueue = function (callback) {
+    //process.nextTick(callback); // NodeJS
+    setTimeout(callback, 1); // Naïve browser solution
+};
+
+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);
+                for (var i = 0, ii = pending.length; i < ii; i++) {
+                    // XXX
+                    enqueue(function () {
+                        value.then.apply(value, pending[i]);
+                    });
+                }
+                pending = undefined;
+            }
+        },
+        promise: {
+            then: function (_callback, _errback) {
+                var result = defer();
+                _callback = _callback || function (value) {
+                    return value;
+                };
+                _errback = _errback || function (reason) {
+                    return reject(reason);
+                };
+                var callback = function (value) {
+                    result.resolve(_callback(value));
+                };
+                var errback = function (reason) {
+                    result.resolve(_errback(reason));
+                };
+                if (pending) {
+                    pending.push([callback, errback]);
+                } else {
+                    // XXX
+                    enqueue(function () {
+                        value.then(callback, errback);
+                    });
+                }
+                return result.promise;
+            }
+        }
+    };
+};
+
+var ref = function (value) {
+    if (value && value.then)
+        return value;
+    return {
+        then: function (callback) {
+            var result = defer();
+            // XXX
+            enqueue(function () {
+                result.resolve(callback(value));
+            });
+            return result.promise;
+        }
+    };
+};
+
+var reject = function (reason) {
+    return {
+        then: function (callback, errback) {
+            var result = defer();
+            // XXX
+            enqueue(function () {
+                result.resolve(errback(reason));
+            });
+            return result.promise;
+        }
+    };
+};
+
+var when = function (value, _callback, _errback) {
+    var result = defer();
+    var done;
+
+    _callback = _callback || function (value) {
+        return value;
+    };
+    _errback = _errback || function (reason) {
+        return reject(reason);
+    };
+
+    // XXX
+    var callback = function (value) {
+        try {
+            return _callback(value);
+        } catch (reason) {
+            return reject(reason);
+        }
+    };
+    var errback = function (reason) {
+        try {
+            return _errback(reason);
+        } catch (reason) {
+            return reject(reason);
+        }
+    };
+
+    enqueue(function () {
+        ref(value).then(function (value) {
+            if (done)
+                return;
+            done = true;
+            result.resolve(ref(value).then(callback, errback));
+        }, function (reason) {
+            if (done)
+                return;
+            done = true;
+            result.resolve(errback(reason));
+        });
+    });
+
+    return result.promise;
+};
+