title: paper autocomplete suggestion source from iron-ajax response
body: <p>I have create autocomplete input using <code>paper-autocomplete-suggestions</code> and I want to get a source from <code>iron-ajax</code> response, here is my code :</p>
  
  <pre><code>&lt;iron-ajax id="procedureSource"
                     url="api.json"&gt;
  &lt;/iron-ajax&gt;
  &lt;template is="dom-repeat" id="sub-intents" items="{{data.data}}"&gt;
       &lt;div class="autocomplete-wrapper"&gt;
            &lt;paper-input name="sub_intent[procedure_id]" id="selectProcedure[[item.id]]" label="Select Procedure" on-keypress="_checkProcedureKeyPress"&gt;&lt;/paper-input&gt;
            &lt;paper-autocomplete-suggestions id="selectProcedureSuggestion[[item.id]]" for="selectProcedure[[item.id]]" remote-source&gt;&lt;/paper-autocomplete-suggestions&gt;
        &lt;/div&gt;
  &lt;/template&gt;
  </code></pre>
  
  <p>I'm using <code>on-keypress</code> event on <code>paper-input</code> to trigger <code>iron-ajax</code> request with input value length should be equal or greater than 3. here is my script :</p>
  
  <pre><code>&lt;script&gt;
  Polymer({
       is: 'input-autocomplete',
       _checkProcedureKeyPress: function (event){
       var keyword = event.target.value;
       var target_id = event.target.closest('paper-input').id.replace('selectProcedure', '');
             if(keyword.length &gt;= 3){
                 this.$.procedureSource.params = {name: keyword};
                 var request = this.$.procedureSource.generateRequest();
                 var p = request.completes;
  
                 p.then(function(xhr, response) {
                     var data = request.response;
                     var autocompleteSuggestions = document.querySelector('#selectProcedureSuggestion' + target_id);
  
                     autocompleteSuggestions.source = data;
                     autocompleteSuggestions.addEventListener('autocomplete-selected', function (event) {
                         var selected = event.detail.text;
                         console.log(selected);
                     });
                 })
             }
  })
  &lt;/script&gt;
  </code></pre>
  
  <p>autocomplete not showing, I'm sure the source is available from <code>iron-ajax</code> response, element target (<code>paper-autocomplete-suggestion</code> element) too.</p>