title: Capybara + Selenium: save_and_open_page shows button, but capybara can't find it
body: <p>My capybara test includes these lines:</p>
  
  <pre><code>click_button "SHARE"
  fill_in 'Email Address', :with =&gt; @user_two.email
  save_and_open_page
  click_button 'CONFIRM'
  </code></pre>
  
  <p>the share button would make a modal visible. Filling in the email address text box of this modal seems to go off without a hitch, but I receive the following error for the button</p>
  
  <pre><code> Capybara::ElementNotFound:
     Unable to find button "CONFIRM"
  </code></pre>
  
  <p>However, when I save_and_open_page, the button is visible.</p>
  
  <p>I've tried switching to     </p>
  
  <pre><code>page.find("#id-of-button").click
  </code></pre>
  
  <p>but Capybara can't find that either.</p>
  
  <p>It's interesting to note the save_and_open_page shows me a page where the field for email hasn't been filled in.</p>
  
  <p>I think I might be missing something basic about how save_and_open_page works because if that is the page Capybara is seeing in its totality then these errors make no sense to me...</p>
  
  <p>edit: Modal view code</p>
  
  <pre><code>.title.aaux
    Title
  .content
    .line-separator
    #intro
      Enter Email:
    = form_for(patient, url: {controller: "dashboard/patients", action: "share_with_user"}, method: :post, html: {id: "share-patient-form"}) do |f|
      %fieldset.bordered
        = f.text_field :share_user_email, placeholder: "Email Address", class: "aaux form-control"
    .line-separator
    #button-row
      %button.btn.btn-success.aaux.pull-right#confirm-share-patient{type: "submit"}
        CONFIRM
      %button.btn.btn-cancel.aaux.pull-right#close-modal-share-patient
        CANCEL
  </code></pre>
  
  <p>edit: source code generated for button</p>
  
  <pre><code>&lt;button type="submit" id="confirm-share-patient-button" class="btn btn-success aaux pull-right"&gt;
  CONFIRM
  &lt;/button&gt;
  </code></pre>