Eliminate legacy support for throw without expression.

runtime/vm/isolate_test.cc

 // Copyright (c) 2012, 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.
 
 #include "platform/assert.h"
 #include "vm/globals.h"
 #include "vm/isolate.h"
 #include "vm/unit_test.h"
 
 namespace dart {
@@ skipping 10 matching lines @@
 // Test to ensure that an exception is thrown if no isolate creation
 // callback has been set by the embedder when an isolate is spawned.
 TEST_CASE(IsolateSpawn) {
   const char* kScriptChars =
       "import 'dart:isolate';\n"
       "void entry() {}\n"
       "int testMain() {\n"
       "  try {\n"
       "    spawnFunction(entry);\n"
       "  } catch (e) {\n"
-      "    throw;\n"
+      "    rethrow;\n"
       "  }\n"
       "  return 0;\n"
       "}\n";
   Dart_Handle lib = TestCase::LoadTestScript(kScriptChars, NULL);
   Dart_Handle result = Dart_Invoke(lib, NewString("testMain"), 0, NULL);
   EXPECT_ERROR(result, "Null callback specified for isolate creation");
   EXPECT(Dart_ErrorHasException(result));
   Dart_Handle exception_result = Dart_ErrorGetException(result);
   EXPECT_VALID(exception_result);
 }
 
 }  // namespace dart