comment entry prod build issues

- angular/angular-cli#7110

Author: myungjaeyu

src/app/pages/board/board-detail/detail-board-comment/detail-comment-entry/detail-comment-entry.component.ts

@@ -1,6 +1,8 @@
 import { Component, OnInit, ViewChild, ElementRef, Input } from '@angular/core';
 
-import { Observable, Subscription } from 'rxjs';
+import { Observable } from 'rxjs/Observable';
+import { Subscription } from 'rxjs/Subscription';
+import 'rxjs/add/observable/timer';
 
 @Component({
   selector: 'app-detail-comment-entry',