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

tests/compiler/dart2js/cps_ir/input/constructor_2.dart

Index: tests/compiler/dart2js/cps_ir/input/constructor_2.dart
diff --git a/tests/compiler/dart2js/cps_ir/input/constructor_2.dart b/tests/compiler/dart2js/cps_ir/input/constructor_2.dart
new file mode 100644
index 0000000000000000000000000000000000000000..23ac512e2d168c446f9a74979552736f2646d42a
--- /dev/null
+++ b/tests/compiler/dart2js/cps_ir/input/constructor_2.dart
@@ -0,0 +1,13 @@
+class Base {
+  var x;
+  Base(this.x);
+}
+class Sub extends Base {
+  var y;
+  Sub(x, this.y) : super(x) {
+    print(x);
+  }
+}
+main() {
+  print(new Sub(1, 2).x);
+}