Fix a type issue with FormView juggling

Summary:
When you click the pencil icon in the Maniphest task list, we currently fatal:

  Argument 1 passed to PhabricatorCustomFieldList::appendFieldsToForm() must be an instance of AphrontFormView, instance of PHUIFormLayoutView given, called in /core/lib/phabricator/src/applications/maniphest/controller/ManiphestTaskEditController.php on line 576 and defined

This is because we build an `AphrontFormView` noramlly, but a `PHUIFormLayoutView` for dialogs, since they don't take a full form (they render their own form tag).

Instead, always build an `AphrontFormView` and just pull the `PHUIFormLayoutView` out of it when we're ready to put it in a dialog. This means `$form` is always the same type of object, and is generally better and makes more sense.

Test Plan: Clicked pencil edit icon in Maniphest task list.

Reviewers: btrahan, chad

Reviewed By: btrahan

CC: aran, carl

Differential Revision: https://secure.phabricator.com/D8324

src/applications/maniphest/controller/ManiphestTaskEditController.php

@@ -460,14 +460,10 @@ final class ManiphestTaskEditController extends ManiphestController {
 
     $project_tokenizer_id = celerity_generate_unique_node_id();
 
-    if ($request->isAjax()) {
-      $form = new PHUIFormLayoutView();
-    } else {
-      $form = new AphrontFormView();
-      $form
-        ->setUser($user)
-        ->addHiddenInput('template', $template_id);
-    }
+    $form = new AphrontFormView();
+    $form
+      ->setUser($user)
+      ->addHiddenInput('template', $template_id);
 
     if ($parent_task) {
       $form
@@ -627,7 +623,7 @@ final class ManiphestTaskEditController extends ManiphestController {
         ->appendChild(
           array(
             $error_view,
-            $form,
+            $form->buildLayoutView(),
           ))
         ->addCancelButton($cancel_uri)
         ->addSubmitButton($button_name);

src/view/form/AphrontFormView.php

@@ -81,12 +81,16 @@ final class AphrontFormView extends AphrontView {
         $this->getUser()));
   }
 
-  public function render() {
-
-    require_celerity_resource('phui-form-view-css');
-    $layout = id (new PHUIFormLayoutView())
+  public function buildLayoutView() {
+    return id(new PHUIFormLayoutView())
       ->appendChild($this->renderDataInputs())
       ->appendChild($this->renderChildren());
+  }
+
+  public function render() {
+    require_celerity_resource('phui-form-view-css');
+
+    $layout = $this->buildLayoutView();
 
     if (!$this->user) {
       throw new Exception(pht('You must pass the user to AphrontFormView.'));