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

tests/compiler/dart2js/cps_ir/input/argument_refinement_11.dart

Index: tests/compiler/dart2js/cps_ir/input/argument_refinement_11.dart
diff --git a/tests/compiler/dart2js/cps_ir/input/argument_refinement_11.dart b/tests/compiler/dart2js/cps_ir/input/argument_refinement_11.dart
new file mode 100644
index 0000000000000000000000000000000000000000..eca781144a895b0a7744aa7393b014838a7f42e5
--- /dev/null
+++ b/tests/compiler/dart2js/cps_ir/input/argument_refinement_11.dart
@@ -0,0 +1,9 @@
+main() {
+  var x = int.parse('1233');
+  var y = int.parse('1234');
+  print(x is num);
+  print(y is num);
+  print(x < y);
+  print(x is num);
+  print(y is num); // will be compiled to `true` if we know the type of `y`.
+}