title: vaadin combobox load wrong custom style
body: <p>In my polymer project , i use a vaadin-combobox in two page like this:
  - page1: i create a custom combobox style file and import to my page:</p>
  
  <pre><code>&lt;link rel="import" href="../elements/base/vaadin-text-field-custom-radius-theme.html"&gt;  
  </code></pre>
  
  <p>content of this file:</p>
  
  <pre><code>&lt;dom-module id="vaadin-text-field-custom-radius-theme" theme-for="vaadin-text-field"&gt;
  &lt;template&gt;
      &lt;style&gt;
          [part="input-field"] {
              border-radius: 2px;
              background-color: white;
              border: 1px solid #808080;
              height: 100%;
              font-family: "Roboto", sans-serif !important;
              color: #4c4c4c !important;
              padding-left: 10px;
              font-size: 14px;
              box-sizing: border-box;
              max-height: 100%;
              background-color: transparent;
              background-image: none !important;
          }
          [part="value"] {
              border: 0px !important;
              box-shadow: none !important;
              height: 100%;
              box-sizing: border-box;
              max-height: 100%;
              background-color: transparent;
              text-align: var(--cmb-align,left);
          }
          .vaadin-text-field {
              height: 100%;
              box-sizing: border-box;
              max-height: 100%;
          }
          .vaadin-text-field-container {
              height: 100%;
              box-sizing: border-box;
              max-height: 100%;
          }
         @media(max-width:1024px){
          [part="input-field"] {
              font-size: 12px !important;
              padding-left: 5px;
          }
          [part="value"] {
              font-size: 12px !important;
          }
          }
      &lt;/style&gt;
  &lt;/template&gt;
  </code></pre>
  
  <p></p>
  
  <p>In page2 ,I have another custom style file with some other css properties.</p>
  
  <p>I use</p>
  
  <pre><code>this.set('route.path',"/page2")
  </code></pre>
  
  <p>to redirect from page1 to page2 and then use</p>
  
  <pre><code> this.set('route.path',"/page1")
  </code></pre>
  
  <p>in page2 to return page1.
  At this time my combobox in page1 is styled by css defined in custom file that i have imported to page 2 ( while i expected it's still styled by css in vaadin-text-field-custom-radius-theme.html").
  Can some one tell me why?</p>
  
  <p>p/s:I tried implement the suggestion of Anton Platonov, but i found that if my page 2 don't import any custom style file, When i return from page2 to page1, the default style of vaadin-text-field that defined in ..\bower_components\vaadin-text-field\vaadin-text-field.html is used for my combobox instead of my vaadin-text-field-custom-radius-theme.html.</p>
  
  <p>If i remove style default in vaadin-text-field.html, my combobox revice css from browser's default  style, still not my vaadin-text-field-custom-radius-theme.html.
  It's treated like my vaadin-text-field-custom-radius-theme no longer exists.</p>
  
  <p>And if i refesh my page 1, everything become normal.
  this is my combobox code:</p>
  
  <pre><code>&lt;vaadin-combo-box-light style="width:100%;height:30px" id="cmdCompanyName" class="fix-size combobox" label="" allow-custom-value items='[[companies]]'
                          value="" item-label-path="name" item-value-path="id" attr-for-selected="id" on-keyup="searchData"
                          on-custom-value-set="searchData2" on-value-changed="searchData2"&gt;
                          &lt;vaadin-text-field style="width:100%;height:30px;" class="cmb-text-field" maxlength="150"&gt;
                              &lt;iron-icon class="prefix" icon="icons:search" slot="prefix"&gt;&lt;/iron-icon&gt;
                              &lt;iron-icon class="suffix toggle-button" slot="suffix" icon="icons:expand-more"&gt;&lt;/iron-icon&gt;
                          &lt;/vaadin-text-field&gt;
                      &lt;/vaadin-combo-box-light&gt;
  </code></pre>