Move generated files to gen/.

test/testing.dart

Index: test/testing.dart
diff --git a/test/testing.dart b/test/testing.dart
index d1335be04f121cb05c2b36b85f0685381534558c..c77708beaffec5dc2137ec77e02eacdb6e613d2a 100644
--- a/test/testing.dart
+++ b/test/testing.dart
@@ -13,6 +13,9 @@ import 'package:path/path.dart' as path;
 final String testDirectory =
     path.dirname((reflectClass(_TestUtils).owner as LibraryMirror).uri.path);
 
+/// The local path to the root directory of the dev_compiler repo.
+final String ddcDirectory = path.dirname(testDirectory);

[Jennifer Messerly, 2016/05/17 17:43:52]

"respositoryDirectory" perhaps?

or "devCompilerDirectory" ?

In code, I avoid the term "DDC" like the plague :). TLAs are hard to understand.
It makes sense to us because we talk about it all the time, but it doesn't
convey meaning to anyone outside the project, so I like to spell it out.

[Bob Nystrom, 2016/05/18 00:12:58]

Good point. Changed to "repoDirectory". I think "repo" is a common abbreviation
(it's what we use when talking out loud).

+
 class _TestUtils {}
 
 class TestUriResolver extends ResourceUriResolver {