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

tests/compiler/dart2js/cps_ir/expected/argument_refinement_27.js

+// Expectation for test: 
+// 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);
+// }
+
+function() {
+  var x = P.int_parse("3", null, null), y = P.int_parse("a", new V.main_closure(), null);
+  P.print(typeof x === "number" && Math.floor(x) === x);
+  P.print(typeof y === "string");
+  P.print(J.codeUnitAt$1$s(y, x));
+  P.print(true);
+  P.print(true);
+}