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

tests/compiler/dart2js/cps_ir/expected/control_flow_9.js

+// Expectation for test: 
+// main() {
+//   var xs = ['x', 'y', 'z'], ys = ['A', 'B', 'C'];
+//   var xit = xs.iterator, yit = ys.iterator;
+//   while (xit.moveNext() && yit.moveNext()) {
+//     print(xit.current);
+//     print(yit.current);
+//   }
+// }
+
+function() {
+  var xs = ["x", "y", "z"], ys = ["A", "B", "C"], i = 0, i1 = 0, current, current1;
+  for (; i < 3; ++i, ++i1) {
+    current = xs[i];
+    if (!(i1 < 3))
+      break;
+    current1 = ys[i1];
+    P.print(current);
+    P.print(current1);
+  }
+}