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

tests/compiler/dart2js/cps_ir/expected/constructor_1.js

+// Expectation for test: 
+// class Base {
+//   var x;
+//   Base(this.x);
+// }
+// class Sub extends Base {
+//   var y;
+//   Sub(x, this.y) : super(x);
+// }
+// main() {
+//   print(new Sub(1, 2).x);
+// }
+
+function() {
+  var line = 1 === 0 ? 1 / 1 < 0 ? "-0.0" : "" + 1 : "" + 1;
+  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);
+  }
+}