title: Flow type checker errors in node_modules/*
body: <p>I've initialized flow project with <code>flow init</code> in fresh <a href="https://github.com/davezuko/react-redux-starter-kit" rel="noreferrer">https://github.com/davezuko/react-redux-starter-kit</a> project. </p>
  
  <p>When Flow does it check, it finds several errors in node_modules. 
  Errors are happening in /* flow */ annotated library files.</p>
  
  <p>It looks like this:</p>
  
  <pre><code>node_modules/editions/source/index.js:33
   33:    const {name, editions} = require(packagePath)
                                   ^^^^^^^^^^^^^^^^^^^^ The parameter passed to require() must be a literal string.
  
  node_modules/fbjs/lib/Deferred.js.flow:60
   60:     Promise.prototype.done.apply(this._promise, arguments);
                             ^^^^ property `done`. Property not found in
  474: declare class Promise&lt;+R&gt; {
       ^ Promise. See lib: /private/tmp/flow/flowlib_d34ebcf/core.js:474
  
  node_modules/fbjs/lib/shallowEqual.js.flow:29
   29:     return x !== 0 || 1 / (x: $FlowIssue) === 1 / (y: $FlowIssue);
                                 ^^^^^^^^^^ identifier `$FlowIssue`.     Could not resolve name
  </code></pre>
  
  <p>Should I make Flow ignoring those files? I assume it may affect type checking correctness.</p>