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

tests/compiler/dart2js/js_backend_cps_ir_interceptors_test.dart

-// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-// Tests of interceptors.
-
-library interceptors_tests;
-
-import 'js_backend_cps_ir.dart';
-
-const List<TestEntry> tests = const [
-  const TestEntry("""
-main() {
-  var g = 1;
-
-  var x = g + 3;
-  print(x);
-}""",
-r"""
-function() {
-  var v0 = H.S(4);
-  if (typeof dartPrint == "function")
-    dartPrint(v0);
-  else if (typeof console == "object" && typeof console.log != "undefined")
-    console.log(v0);
-  else if (!(typeof window == "object")) {
-    if (!(typeof print == "function"))
-      throw "Unable to print message: " + String(v0);
-    print(v0);
-  }
-}"""),
-  const TestEntry("""
-main() {
-  var l = ['hest', ['h', 'e', 's', 't']];
-  print(l.length);
-  for (int i  = 0; i < l.length; i++) {
-    var x = l[i];
-    for (int j = 0; j < x.length; j++) {
-      print(x[j]);
-    }
-  }
-}""",
-r"""
-function() {
-  var l = ["hest", ["h", "e", "s", "t"]], i = 0, x, j;
-  for (P.print(2); i < 2; ++i) {
-    x = l[i];
-    for (j = 0; j < x.length; ++j)
-      P.print(x[j]);
-  }
-}"""),
-];
-
-
-void main() {
-  runTests(tests);
-}