Don't show the "file tree" view on tablets/phones

Summary: Ref T13516. Hide this UI on devices without the screen width to reasonably support it.

Test Plan: Viewed a revision at various window widths, saw the elements vanish at device widths and reappear at desktop widths.

Maniphest Tasks: T13516

Differential Revision: https://secure.phabricator.com/D21162

resources/celerity/map.php

···
     'rsrc/css/phui/phui-fontkit.css' => '1ec937e5',
     'rsrc/css/phui/phui-form-view.css' => '01b796c0',
     'rsrc/css/phui/phui-form.css' => '1f177cb7',
-    'rsrc/css/phui/phui-formation-view.css' => '9a1eff7e',
+    'rsrc/css/phui/phui-formation-view.css' => '1e6b744b',
     'rsrc/css/phui/phui-head-thing.css' => 'd7f293df',
     'rsrc/css/phui/phui-header-view.css' => '36c86a58',
     'rsrc/css/phui/phui-hovercard.css' => '6ca90fa0',
···
     'phui-fontkit-css' => '1ec937e5',
     'phui-form-css' => '1f177cb7',
     'phui-form-view-css' => '01b796c0',
-    'phui-formation-view-css' => '9a1eff7e',
+    'phui-formation-view-css' => '1e6b744b',
     'phui-head-thing-view-css' => 'd7f293df',
     'phui-header-view-css' => '36c86a58',
     'phui-hovercard' => '074f0783',

src/applications/differential/engine/DifferentialFileTreeEngine.php

···
       ->setIsResizable(true)
       ->setIsFixed(true)
       ->setIsVisible($is_visible)
+      ->setIsDesktopOnly(true)
       ->setWidth($width)
       ->setMinimumWidth($this->getMinimumWidth())
       ->setMaximumWidth($this->getMaximumWidth());

src/view/formation/PHUIFormationColumnView.php

···
   extends AphrontAutoIDView {
 
   private $item;
+  private $isDesktopOnly;
 
   final public function setColumnItem(PHUIFormationColumnItem $item) {
     $this->item = $item;
···
 
   public function getExpanderTooltip() {
     return null;
+  }
+
+  public function setIsDesktopOnly($is_desktop_only) {
+    $this->isDesktopOnly = $is_desktop_only;
+    return $this;
+  }
+
+  public function getIsDesktopOnly() {
+    return $this->isDesktopOnly;
   }
 
 }

src/view/formation/PHUIFormationView.php

···
         $style[] = 'display: none;';
       }
 
+      $classes = array();
+      if ($column->getIsDesktopOnly()) {
+        $classes[] = 'phui-formation-desktop-only';
+      }
+
       $cells[] = phutil_tag(
         'td',
         array(
           'id' => $item->getID(),
           'style' => implode(' ', $style),
+          'class' => implode(' ', $classes),
         ),
         array(
           $column,
···
         $resizer_item = $this->newResizerItem();
         $item->setResizerItem($resizer_item);
 
-        $resizer_item
-          ->getColumn()
+        $resizer_item->getColumn()
+          ->setIsDesktopOnly($column->getIsDesktopOnly())
           ->setIsVisible($column->getIsVisible());
       }
 

webroot/rsrc/css/phui/phui-formation-view.css

···
   border-color: {$lightgreyborder};
   background: {$lightgreybackground};
   z-index: 4;
+
+  display: none;
+}
+
+.device-desktop .phui-formation-view-expander {
+  display: block;
+}
+
+.phui-formation-desktop-only {
+  display: none;
+}
+
+.device-desktop .phui-formation-desktop-only {
+  display: table-cell;
 }
 
 .phui-formation-view-expander-left {
···
   background-image: url(/rsrc/image/divot.png);
   background-position: center;
   background-repeat: no-repeat;
+
+  display: none;
+}
+
+.device-desktop .phui-formation-resizer {
+  display: block;
 }
 
 .phui-flank-view-fixed {