tests: Add a test for using the same selector multiple times

tests/css/parser/Makefile.am

@@ -263,6 +263,8 @@ EXTRA_DIST += \
 	does-not-exist.css \
 	does-not-exist.errors \
 	does-not-exist.ref.css \
+	doubled.css \
+	doubled.ref.css \
 	empty.css \
 	enum.css \
 	enum.errors \

tests/css/parser/doubled.css

@@ -0,0 +1,12 @@
+.class.class { color: red; }
+.class { color: red; }
+
+#name#name#name { color: red; }
+#name { color: red; }
+
+:focus:focus { color: red; }
+:focus { color: red; }
+
+:nth-child(even):nth-child(even):nth-child(even) { color: red; }
+:nth-child(even) { color: red; }
+

tests/css/parser/doubled.ref.css

@@ -0,0 +1,31 @@
+.class {
+  color: rgb(255,0,0);
+}
+
+:focus {
+  color: rgb(255,0,0);
+}
+
+:nth-child(even) {
+  color: rgb(255,0,0);
+}
+
+.class.class {
+  color: rgb(255,0,0);
+}
+
+:focus:focus {
+  color: rgb(255,0,0);
+}
+
+:nth-child(even):nth-child(even):nth-child(even) {
+  color: rgb(255,0,0);
+}
+
+#name {
+  color: rgb(255,0,0);
+}
+
+#name#name#name {
+  color: rgb(255,0,0);
+}