title: ESLint no-undef on ES6 function with named arguments
body: <p>I have a function defined like this:</p>
  
  <pre><code>const generate = (report={}, buffer=false) =&gt; {
    // do stuff
  }
  </code></pre>
  
  <p>Notice how both of the parameters have default values.</p>
  
  <p>When I call that function and name an argument I get a no-undef ESLint error.</p>
  
  <pre><code>generate(buffer = true);
  </code></pre>
  
  <p>ESLint says that "buffer" is not defined. It's not detecting that it is a named argument. Does anyone know how to change my .eslintrc to account for named arguments. I can't find anything online.</p>
  
  <p>Thanks in advance!</p>