Add unit test crate for stylo

tests/unit/stylo/Cargo.toml

@@ -0,0 +1,16 @@
+[package]
+name = "stylo_tests"
+version = "0.0.1"
+authors = ["The Servo Project Developers"]
+license = "MPL-2.0"
+
+[lib]
+name = "stylo_tests"
+path = "lib.rs"
+doctest = false
+
+[dependencies]
+app_units = "0.3"
+cssparser = {version = "0.7", features = ["heap_size"]}
+style = {path = "../../../components/style", features = ["gecko"]}
+style_traits = {path = "../../../components/style_traits"}

tests/unit/stylo/lib.rs

@@ -0,0 +1,10 @@
+extern crate app_units;
+extern crate cssparser;
+extern crate style;
+extern crate style_traits;
+
+#[test]
+fn test_test() {
+    // do nothing
+    // this is a temporary test testing that the test runs
+}