fix(@angular-devkit/core): record host should stat backing host

Author: clydin

packages/angular_devkit/core/src/virtual-fs/host/record.ts

@@ -26,6 +26,7 @@ import {
   HostCapabilities,
   HostWatchOptions,
   ReadonlyHost,
+  Stats,
 } from './interface';
 import { SimpleMemoryHost } from './memory';
 
@@ -366,6 +367,12 @@ export class CordHost extends SimpleMemoryHost {
       : ((this.willDelete(path) || this.willRename(path)) ? of(false) : this._back.isFile(path));
   }
 
+  stat(path: Path): Observable<Stats | null> | null {
+    return this._exists(path)
+      ? super.stat(path)
+      : ((this.willDelete(path) || this.willRename(path)) ? of(null) : this._back.stat(path));
+  }
+
   watch(path: Path, options?: HostWatchOptions) {
     // Watching not supported.
     return null;