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

tests/compiler/dart2js/cps_ir/expected/closures_10.js

+// Expectation for test: 
+// class A {
+//   a() => 1;
+//   b() => () => a();
+// }
+// main() {
+//   print(new A().b()());
+// }
+
+function() {
+  var line = H.S(new V.A_b_closure(V.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);
+  }
+}