title: Angular Material: 'md-card-title-text' is not a known element
body: <p>using Angular v5 with Angular Material v5. </p>
  
  <p>markup: </p>
  
  <pre><code>  &lt;md-card md-theme="'dark-blue'" md-theme-watch&gt;
      &lt;md-card-title&gt;
         &lt;md-card-title-text&gt;
  </code></pre>
  
  <blockquote>
    <p>Uncaught Error: Template parse errors: 'md-card-title-text' is not a
    known element:
    1. If 'md-card-title-text' is an Angular component, then verify that it is part of this module.</p>
  </blockquote>
  
  <p>my module.ts</p>
  
  <pre><code>import { BrowserModule } from '@angular/platform-browser';
  import { NgModule } from '@angular/core';
  import { BrowserAnimationsModule } from '@angular/platform-browser/animations';
  import { MatButtonModule, MatCheckboxModule, MatIconModule, MatMenuModule, MatCardModule } from '@angular/material';
  ...
  @NgModule({
    declarations: [
      AppComponent,
    ],
    imports: [
        BrowserModule,
        BrowserAnimationsModule,
        MatButtonModule, MatCheckboxModule, 
        MatMenuModule,
        MatIconModule,
        MatCardModule
    ],
    providers: [...],
    bootstrap: [AppComponent]
  })
  export class AppModule { }
  </code></pre>
  
  <p>the other Material elements on my page work fine. md-card parses fine after I added MatCardModule. </p>
  
  <p>what's perplexing is why adding MatCardModule worked to fix any md-card issues, but not md-card-title-text</p>