build: Move tests/reftests to testsuite/reftests

testsuite/reftests/border-style.css

@@ -0,0 +1,27 @@
+@import url("reset-to-defaults.css");
+
+GtkButton {
+  background-color: red;
+  border-color: lime;
+  border-width: 1px;
+}
+
+.button-top-left {
+  border-style: solid none none solid;
+}
+
+.button-top-right {
+  border-style: solid solid none none;
+}
+
+.button-bottom-left {
+  border-style: none none solid solid;
+}
+
+.button-bottom-right {
+  border-style: none solid solid none;
+}
+
+.button-border {
+  border-style: solid;
+}