Don’t take time to run 0 in-crate unit tests

Cargo.toml

@@ -18,6 +18,9 @@ name = "tests"
 name = "wpt"
 harness = false
 
+[lib]
+test = false
+
 [dev-dependencies]
 rustc-test = "0.1"
 rustc-serialize = "0.3"