title: Add custom elements and attributes to compiler schema
body: <p>There are some custom elements and attributes in component template (in this example they are used by third-party non-Angular code):</p>
  
  <pre><code>&lt;foo&gt;&lt;/foo&gt;
  &lt;div data-bar="{{ bar }}"&gt;&lt;/div&gt;
  </code></pre>
  
  <p>They cause a compiler error:</p>
  
  <pre><code>Template parse errors:
  'foo' is not a known element:
  1. If 'foo' is an Angular component, then verify that it is part of this module.
  2. If 'foo' is a Web Component then add "CUSTOM_ELEMENTS_SCHEMA" to the '@NgModule.schemas' of this component to suppress this message. ("
      [ERROR -&gt;]&lt;foo&gt;&lt;/foo&gt;
      &lt;div data-bar="{{ bar }}"&gt;&lt;/div&gt;
    "): App@1:4
  Can't bind to 'bar' since it isn't a known property of 'div'. ("
      &lt;foo&gt;&lt;/foo&gt;
      &lt;div [ERROR -&gt;]data-bar="{{ bar }}"&gt;&lt;/div&gt;
    ")
  ...
  </code></pre>
  
  <p>How can <code>foo</code> element and <code>data-bar</code> attribute be added to compiler schema?</p>
  
  <p><code>NO_ERRORS_SCHEMA</code> is not an option because it is not desirable for other unknown elements and attributes to be whitelisted.</p>