Update dartium DEPS to use co19 from github.

tools/deps/dartium.deps/DEPS

Index: tools/deps/dartium.deps/DEPS
diff --git a/tools/deps/dartium.deps/DEPS b/tools/deps/dartium.deps/DEPS
index 1977d7a6a69b7330a69683d27e08f5c286329fef..e7fef5839b8b3a2337f7a9e33135d4fe03b97137 100644
--- a/tools/deps/dartium.deps/DEPS
+++ b/tools/deps/dartium.deps/DEPS
@@ -53,7 +53,7 @@ vars.update({
   "zlib_rev": "@c3d0a6190f2f8c924a05ab6cc97b8f975bddd33f",
   "web_components_rev": "@0e636b534d9b12c9e96f841e6679398e91a986ec",
 
-  "co19_rev": "@801",
+  "co19_rev": "@f95f109fea67127a220958794ef5200a63cb454c",

[terry, 2015/08/14 16:07:48]

The SHA1 should be 34010003cd3e74085084c92816247b53cc8be491 however, I can do
that after your CL.  The hash your using is where I started the co91 integration
branch the above hash are my changes.

   "fake_async_rev": "@38614",
 })
 
@@ -177,8 +177,8 @@ deps.update({
     "http://dart.googlecode.com/svn/third_party/fake_async" +
     Var("fake_async_rev"),
 
-  "src/dart/tests/co19/src": ((Var("googlecode_url") % "co19") +
-    "/trunk/co19/tests/co19/src" + Var("co19_rev")),
+  "src/dart/tests/co19/src":
+      "https://github.com/dart-lang/co19.git" + Var("co19_rev"),
 
   "src/dart/third_party/zlib":
       Var("chromium_git") + "/chromium/src/third_party/zlib.git" +