build: move zone.js to angular repo (#30962)

PR Close #30962

packages/zone.js/example/js/counting-zone.js

@@ -0,0 +1,33 @@
+/*
+ * See example/counting.html
+ */
+
+Zone['countingZoneSpec'] = {
+  name: 'counterZone',
+  // setTimeout
+  onScheduleTask: function(delegate, current, target, task) {
+    this.data.count += 1;
+    delegate.scheduleTask(target, task);
+  },
+
+  // fires when...
+  // - clearTimeout
+  // - setTimeout finishes
+  onInvokeTask: function(delegate, current, target, task, applyThis, applyArgs) {
+    delegate.invokeTask(target, task, applyThis, applyArgs);
+    this.data.count -= 1;
+  },
+
+  onHasTask: function(delegate, current, target, hasTask) {
+    if (this.data.count === 0 && !this.data.flushed) {
+      this.data.flushed = true;
+      target.run(this.onFlush);
+    }
+  },
+
+  counter: function() { return this.data.count; },
+
+  data: {count: 0, flushed: false},
+
+  onFlush: function() {}
+};