Add a "document" style to PHUIRemarkupPreviewPanel and use it in Legalpad and Phriction

Summary: Ref T3671. Depends on D6674. Continues work in D6673, D6674 and extends it into Legalpad and Phriction. Then deletes a bunch of dead code.

Test Plan: Edited documents in Legalpad and Phriction, verified I got reasonable looking previews.

Reviewers: btrahan, Firehed

Reviewed By: btrahan

CC: aran, chad

Maniphest Tasks: T3671

Differential Revision: https://secure.phabricator.com/D6675

src/applications/phriction/controller/PhrictionEditController.php

@@ -229,24 +229,11 @@ final class PhrictionEditController
     $header = id(new PhabricatorHeaderView())
       ->setHeader($panel_header);
 
-    $preview_content = hsprintf(
-      '<div class="phriction-document-preview-header plt pll">%s</div>
-      <div id="document-preview">
-        <div class="aphront-panel-preview-loading-text">%s</div>
-      </div>',
-      pht('Document Preview'),
-      pht('Loading preview...'));
-
-    $preview_panel = id(new PHUIDocumentView())
-      ->appendChild($preview_content);
-
-    Javelin::initBehavior(
-      'phriction-document-preview',
-      array(
-        'preview'   => 'document-preview',
-        'textarea'  => 'document-textarea',
-        'uri'       => '/phriction/preview/?draftkey='.$draft_key,
-      ));
+    $preview = id(new PHUIRemarkupPreviewPanel())
+      ->setHeader(pht('Document Preview'))
+      ->setPreviewURI('/phriction/preview/')
+      ->setControlID('document-textarea')
+      ->setSkin('document');
 
     $crumbs = $this->buildApplicationCrumbs();
     if ($document->getID()) {
@@ -269,7 +256,7 @@ final class PhrictionEditController
         $draft_note,
         $error_view,
         $form,
-        $preview_panel,
+        $preview,
       ),
       array(
         'title'   => pht('Edit Document'),