Hook up the dartdoc tests to test.py, test.dart, and frog/presubmit.py.

utils/tests/dartdoc/src/markdown_tests.dart

Index: utils/tests/dartdoc/src/markdown_tests.dart
diff --git a/utils/dartdoc/test/markdown_tests.dart b/utils/tests/dartdoc/src/markdown_tests.dart
similarity index 99%
rename from utils/dartdoc/test/markdown_tests.dart
rename to utils/tests/dartdoc/src/markdown_tests.dart
index e2d7312cf694541fa78c067e48817cdfb4dbdcab..23801810af4c999adff67f85b3c57097ead8b043 100644
--- a/utils/dartdoc/test/markdown_tests.dart
+++ b/utils/tests/dartdoc/src/markdown_tests.dart
@@ -5,10 +5,10 @@
 /// Unit tests for markdown.
 #library('markdown_tests');
 
-#import('../markdown.dart');
+#import('../../../dartdoc/markdown.dart');
 
 // TODO(rnystrom): Better path to unittest.
-#import('../../../client/testing/unittest/unittest_vm.dart');
+#import('../../../../client/testing/unittest/unittest_node.dart');
 
 /// Most of these tests are based on observing how showdown behaves:
 /// http://softwaremaniacs.org/playground/showdown-highlight/