title: breaking exception '_InternalLinkedHashMap<dynamic, dynamic>' is not a subtype of type 'Map<String, String>'
body: <p>I ran a flutter upgrade today...</p>
  <p>I'm now on v0.2.11 and I'm getting a strange runtime error in this function:</p>
  <pre><code>Future apiCall([Map params = const {}]) async {
    loading = true;
    Map stringParams = {};
    params.forEach((k,v)=&gt;stringParams[k.toString()] = v.toString());
    Uri url = new Uri.https(apiDomain, apiPath, stringParams);
    print(url);
    var result = await http.post(
      url,
      body: {'apikey': apiKey}
    );
    loading = false;
    print(result.body);
    return json.decode(result.body);
  }
  </code></pre>
  <p>I'm calling the function without any params and I get the subtype error.</p>
  <p>This code works in DartPad.</p>
  <p>Does anyone have an idea what might be going on?</p>