Update dartdoc to v0.13.0+1.

DEPS

Index: DEPS
diff --git a/DEPS b/DEPS
index c34607ec3acd4f05b8c1e4c08dc7e827e1cbf43e..5aa09dfa3b60695c04d5368026eeedd8e8aa9bfe 100644
--- a/DEPS
+++ b/DEPS
@@ -66,7 +66,7 @@ vars = {
   "dart2js_info_tag" : "@0.5.4+2",
   "dart_services_rev" : "@7aea2574e6f3924bf409a80afb8ad52aa2be4f97",
   "dart_style_tag": "@1.0.6",
-  "dartdoc_tag" : "@v0.12.0",
+  "dartdoc_tag" : "@v0.13.0+1",
   "fixnum_tag": "@0.10.5",
   "func_tag": "@1.0.0",
   "glob_tag": "@1.1.3",
@@ -83,7 +83,7 @@ vars = {
   "json_rpc_2_tag": "@2.0.4",
   "linter_tag": "@0.1.31",
   "logging_tag": "@0.11.3+1",
-  "markdown_tag": "@0.11.2",
+  "markdown_tag": "@0.11.3",
   "matcher_tag": "@0.12.0+2",
   "metatest_tag": "@0.2.2+3",
   "mime_rev": "@75890811d4af5af080351ba8a2853ad4c8df98dd",