chore: lint error (#8086)

Fixes a linting error in the docs

Author: crisbeto

src/material-examples/table-http/table-http-example.ts

@@ -1,4 +1,4 @@
-import {Component, OnInit, ViewChild} from '@angular/core';
+import {Component, AfterViewInit, ViewChild} from '@angular/core';
 import {HttpClient} from '@angular/common/http';
 import {MatPaginator, MatSort, MatTableDataSource} from '@angular/material';
 import {Observable} from 'rxjs/Observable';
@@ -17,7 +17,7 @@ import 'rxjs/add/operator/switchMap';
   styleUrls: ['table-http-example.css'],
   templateUrl: 'table-http-example.html',
 })
-export class TableHttpExample {
+export class TableHttpExample implements AfterViewInit {
   displayedColumns = ['created', 'state', 'number', 'title'];
   exampleDatabase: ExampleHttpDao | null;
   dataSource = new MatTableDataSource();