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

tests/compiler/dart2js/cps_ir/expected/closures_9.js

+// Expectation for test: 
+// main() {
+//   var a;
+//   for (var i=0; i<10; i++) {
+//     a = () => i;
+//   }
+//   print(a());
+// }
+
+function() {
+  var a = null, i = 0, line;
+  for (; i < 10; a = new V.main_closure(i), ++i)
+    ;
+  line = H.S(a.call$0());
+  if (typeof dartPrint == "function")
+    dartPrint(line);
+  else if (typeof console == "object" && typeof console.log != "undefined")
+    console.log(line);
+  else if (!(typeof window == "object")) {
+    if (!(typeof print == "function"))
+      throw "Unable to print message: " + String(line);
+    print(line);
+  }
+}