title: Template parse errors: 'mat-icon' is not a known element
body: <p>I'm working with Angular CLI and angular material v.5.2.5
  and trying to use</p>
  <blockquote>
  <p>mat-icon-button</p>
  </blockquote>
  <p>but such an error produced by the console:</p>
  <blockquote>
  <p>Uncaught Error: Template parse errors: 'mat-icon' is not a known
  element...</p>
  </blockquote>
  <p>if I use</p>
  <blockquote>
  <p>mat-raised-button</p>
  </blockquote>
  <p>everything works fine
  cannot figure out how to solve that</p>
  <p>index.html</p>
  <pre class="lang-html prettyprint-override"><code> &lt;!doctype html&gt;
  &lt;html lang=&quot;en&quot;&gt;
  &lt;head&gt;
    &lt;meta charset=&quot;utf-8&quot;&gt;
    &lt;title&gt;Todo&lt;/title&gt;
    &lt;base href=&quot;/&quot;&gt;
  
    &lt;meta name=&quot;viewport&quot; content=&quot;width=device-width, initial-scale=1&quot;&gt;
    &lt;link href=&quot;https://fonts.googleapis.com/css?family=Roboto:300,400,500,700,400italic&quot;
      rel=&quot;stylesheet&quot;&gt;
    &lt;link href=&quot;https://fonts.googleapis.com/icon?family=Material+Icons&quot; rel=&quot;stylesheet&quot;&gt;
  &lt;/head&gt;
  &lt;body&gt;
    &lt;app-root&gt;&lt;/app-root&gt;
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  <p>main.ts</p>
  <pre><code> import { enableProdMode } from '@angular/core';
  import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
  
  import { AppModule } from './app/app.module';
  import { environment } from './environments/environment';
  
  if (environment.production) {
    enableProdMode();
  }
  
  platformBrowserDynamic().bootstrapModule(AppModule)
    .catch(err =&gt; console.log(err));
  </code></pre>
  <p>app.module.ts</p>
  <pre><code> import { BrowserModule } from '@angular/platform-browser';
  import { NgModule } from '@angular/core';
  import { FormsModule } from '@angular/forms';
  import { HttpModule } from '@angular/http';
  import { MatButtonModule } from '@angular/material/button';
  
  
  import { AppComponent } from './app.component';
  
  
  @NgModule({
    declarations: [
      AppComponent
    ],
    imports: [
      BrowserModule,
      FormsModule,
      HttpModule,
      MatButtonModule
    ],
    providers: [],
    bootstrap: [AppComponent]
  })
  export class AppModule { }
  </code></pre>