Make AphrontProxyResponse reduce to a real response instead of building a string

Summary: Currently, AphrontProxyResponse is expected to build a string. This prevents some response types (like Dialog) from being proxied, because they have special rules. Instead, make proxy responses reduce into a non-proxied response so it's possible to proxy any type of response and hit all the normal rules for it.

Test Plan: Built a proxied DialogResponse on top of this.

Reviewers: btrahan, vrana

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T2104, T912

Differential Revision: https://secure.phabricator.com/D4159

src/infrastructure/diff/PhabricatorChangesetResponse.php

@@ -19,7 +19,7 @@ final class PhabricatorChangesetResponse extends AphrontProxyResponse {
     return new AphrontAjaxResponse();
   }
 
-  public function buildResponseString() {
+  public function reduceProxyResponse() {
     $content = array(
       'changeset' => $this->renderedChangeset,
     );
@@ -28,7 +28,7 @@ final class PhabricatorChangesetResponse extends AphrontProxyResponse {
       $content['coverage'] = $this->coverage;
     }
 
-    return $this->getProxy()->setContent($content)->buildResponseString();
+    return $this->getProxy()->setContent($content);
   }
 
 }