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

tests/compiler/dart2js/cps_ir/input/argument_refinement_27.dart

Index: tests/compiler/dart2js/cps_ir/input/argument_refinement_27.dart
diff --git a/tests/compiler/dart2js/cps_ir/input/argument_refinement_27.dart b/tests/compiler/dart2js/cps_ir/input/argument_refinement_27.dart
new file mode 100644
index 0000000000000000000000000000000000000000..b53d2df59333177e790c78ead4ee2bc03d8b4f59
--- /dev/null
+++ b/tests/compiler/dart2js/cps_ir/input/argument_refinement_27.dart
@@ -0,0 +1,9 @@
+main() {
+  var x = int.parse('3');
+  var y = int.parse('a', onError: (e) => 'abcde');
+  print(x is int);
+  print(y is String);
+  print(y.codeUnitAt(x));
+  print(x is int);
+  print(y is String);
+}