title: What is the equivalent of Object.assign in Dart?
body: <p>in javascript whe have Object.assign
  and we can use them like this:</p>
  <pre class="lang-js prettyprint-override"><code>var a = {name:'car', value: 2}
  var b = {name:'car', value: 65, speed: 100}
  var c = {name:'car', value: 5}
  var result = {}
  Object.assign(result, a)
  Object.assign(result, b)
  Object.assign(result, c)
  // result == {name: &quot;car&quot;, value: 5, speed: 100}
  </code></pre>
  <p>how i can make that in dart?</p>