Retire vendored cacycle_diff.js for a diff-lcs-based diff view

Revisions#diff now computes an inline or side-by-side word diff
server-side (Page#diff_against, lib/html_word_diff.rb) instead of
shipping raw/escaped content to the browser for a 2008-era vendored
JS differ to mangle. View mode is picked via a `view` param, settable
either on the diff page itself or directly from the revisions#index
sticky bar next to "Diff revisions".

Also fixes a pre-existing bug in RevisionsController#diff's single-
revision branch, which set params[:start]/params[:end] instead of
params[:start_revision]/params[:end_revision].

1 files changed, 8 insertions, 0 deletions

diff --git a/app/views/revisions/index.html.erb b/app/views/revisions/index.html.erb
index a6a981af..58c08b70 100644
--- a/app/views/revisions/index.html.erb
+++ b/app/views/revisions/index.html.erb
@@ -19,6 +19,8 @@
               form: { id: 'diff_form', class: 'button_to computation' },
               disabled: true %>
         <span id="diff_selection_label"></span>
+        <label><%= radio_button_tag :view, 'inline', true %> Inline</label>
+        <label><%= radio_button_tag :view, 'side_by_side', false %> Side by side</label>
       </td>
     </tr>
   </thead>
@@ -68,6 +70,7 @@
   document.getElementById('diff_form').addEventListener('submit', function(e) {
     var start = document.querySelector('input[name="start_revision"]:checked');
     var end = document.querySelector('input[name="end_revision"]:checked');
+    var view = document.querySelector('input[name="view"]:checked');
     if (start) {
       var s = document.createElement('input');
       s.type = 'hidden'; s.name = 'start_revision'; s.value = start.value;
@@ -78,5 +81,10 @@
       en.type = 'hidden'; en.name = 'end_revision'; en.value = end.value;
       this.appendChild(en);
     }
+    if (view) {
+      var v = document.createElement('input');
+      v.type = 'hidden'; v.name = 'view'; v.value = view.value;
+      this.appendChild(v);
+    }
   });
 </script>