cpsir unittests: move all unittests into individual files and test runners.

tests/compiler/dart2js/cps_ir/expected/closures_2.js

Index: tests/compiler/dart2js/cps_ir/expected/closures_2.js
diff --git a/tests/compiler/dart2js/cps_ir/expected/closures_2.js b/tests/compiler/dart2js/cps_ir/expected/closures_2.js
new file mode 100644
index 0000000000000000000000000000000000000000..b5ffeebd4af83d516691183f9f82757a10eb7917
--- /dev/null
+++ b/tests/compiler/dart2js/cps_ir/expected/closures_2.js
@@ -0,0 +1,17 @@
+// Expectation for test: 
+// main(x) {
+//   a() {
+//     return x;
+//   }
+//   x = x + '1';
+//   print(a());
+//   return a;
+// }
+
+function(x) {
+  var _box_0 = {}, a = new V.main_a(_box_0);
+  _box_0.x = x;
+  _box_0.x = J.$add$ns(_box_0.x, "1");
+  P.print(a.call$0());
+  return a;
+}