Fix prints/throws tests on the latest dart2js.

test/frontend/matcher/throws_test.dart

 // Copyright (c) 2015, 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.
 
 import 'dart:async';
 
 import 'package:test/test.dart';
 
 import '../../utils.dart';
 
 void main() {
   group("synchronous", () {
     group("[throws]", () {
       test("with a function that throws an error", () {
         expect(() => throw 'oh no', throws);
       });
 
       test("with a function that doesn't throw", () async {
+        var closure = () {};
         var liveTest = await runTestBody(() {
-          expect(() {}, throws);
+          expect(closure, throws);
         });
 
-        expectTestFailed(liveTest,
-            "Expected: throws\n"
-            "  Actual: <$closureString>\n"
-            "   Which: did not throw\n");
+        expectTestFailed(liveTest, allOf([
+          startsWith(
+              "Expected: throws\n"
+              "  Actual: <"),
+          endsWith(">\n"
+              "   Which: did not throw\n")
+        ]));
       });
 
       test("with a non-function", () async {
         var liveTest = await runTestBody(() {
           expect(10, throws);
         });
 
         expectTestFailed(liveTest,
             "Expected: throws\n"
             "  Actual: <10>\n"
             "   Which: is not a Function or Future\n");
       });
     });
 
     group("[throwsA]", () {
       test("with a function that throws an identical error", () {
         expect(() => throw 'oh no', throwsA('oh no'));
       });
 
       test("with a function that throws a matching error", () {
         expect(() => throw new FormatException("bad"),
             throwsA(isFormatException));
       });
 
       test("with a function that doesn't throw", () async {
+        var closure = () {};
         var liveTest = await runTestBody(() {
-          expect(() {}, throwsA('oh no'));
+          expect(closure, throwsA('oh no'));
         });
 
-        expectTestFailed(liveTest,
-            "Expected: throws 'oh no'\n"
-            "  Actual: <$closureString>\n"
-            "   Which: did not throw\n");
+        expectTestFailed(liveTest, allOf([
+          startsWith(
+              "Expected: throws 'oh no'\n"
+              "  Actual: <"),
+          endsWith(">\n"
+              "   Which: did not throw\n")
+        ]));
       });
 
       test("with a non-function", () async {
         var liveTest = await runTestBody(() {
           expect(10, throwsA('oh no'));
         });
 
         expectTestFailed(liveTest,
             "Expected: throws 'oh no'\n"
             "  Actual: <10>\n"
             "   Which: is not a Function or Future\n");
       });
 
       test("with a function that throws the wrong error", () async {
         var liveTest = await runTestBody(() {
           expect(() => throw 'aw dang', throwsA('oh no'));
         });
 
-        expectTestFailed(liveTest,
-            "Expected: throws 'oh no'\n"
-            "  Actual: <$closureString>\n"
-            "   Which: threw 'aw dang'\n");
+        expectTestFailed(liveTest, allOf([
+          startsWith(
+              "Expected: throws 'oh no'\n"
+              "  Actual: <"),
+          endsWith(">\n"
+              "   Which: threw 'aw dang'\n")
+        ]));
       });
     });
   });
 
   group("asynchronous", () {
     group("[throws]", () {
       test("with a Future that throws an error", () {
         expect(new Future.error('oh no'), throws);
       });
 
@@ skipping 32 matching lines @@
 
         expectTestFailed(liveTest,
             "Expected future to fail, but succeeded with 'null'.");
       });
 
       test("with a Future that throws the wrong error", () async {
         var liveTest = await runTestBody(() {
           expect(new Future.error('aw dang'), throwsA('oh no'));
         });
 
-        expectTestFailed(liveTest, startsWith(
-            "Expected: throws 'oh no'\n"
-            "  Actual: <$closureString>\n"
-            "   Which: threw 'aw dang'\n"));
+        expectTestFailed(liveTest, allOf([
+          startsWith(
+              "Expected: throws 'oh no'\n"
+              "  Actual: <"),
+          contains(">\n"
+              "   Which: threw 'aw dang'\n")
+        ]));
       });
 
       test("won't let the test end until the Future completes", () {
         return expectTestBlocks(() {
           var completer = new Completer();
           expect(completer.future, throwsA('oh no'));
           return completer;
         }, (completer) => completer.completeError('oh no'));
       });
     });
   });
 }