[VM logging] Fix nesting of log blocker (second attempt).

runtime/vm/log_test.cc

 // 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.
 
 #include "platform/globals.h"
 
 #include "include/dart_tools_api.h"
 #include "vm/dart_api_impl.h"
 #include "vm/dart_entry.h"
 #include "vm/debugger.h"
@@ skipping 18 matching lines @@
   va_list args2;
   va_start(args2, format);
   OS::VSNPrint(buffer, (len + 1), format, args2);
   va_end(args2);
 
   if (test_output_ != NULL) {
     free(const_cast<char*>(test_output_));
     test_output_ = NULL;
   }
   test_output_ = buffer;
+
+  // Also print to stdout to see the overall result.
+  OS::Print("%s", test_output_);
 }
 
 class LogTestHelper : public AllStatic {
  public:
   static void SetPrinter(Log* log, LogPrinter printer) {
     ASSERT(log != NULL);
     ASSERT(printer != NULL);
     log->printer_ = printer;
   }
 
@@ skipping 36 matching lines @@
   EXPECT_EQ(reinterpret_cast<const char*>(NULL), test_output_);
   {
     LogBlock ba(thread, log);
     log->Print("APPLE");
     EXPECT_EQ(reinterpret_cast<const char*>(NULL), test_output_);
     {
       LogBlock ba(thread, log);
       log->Print("BANANA");
       EXPECT_EQ(reinterpret_cast<const char*>(NULL), test_output_);
     }
-    EXPECT_STREQ("BANANA", test_output_);
+    EXPECT_EQ(reinterpret_cast<const char*>(NULL), test_output_);
+    {
+      LogBlock ba(thread, log);
+      log->Print("PEAR");
+      EXPECT_EQ(reinterpret_cast<const char*>(NULL), test_output_);
+    }
+    EXPECT_EQ(reinterpret_cast<const char*>(NULL), test_output_);
   }
-  EXPECT_STREQ("APPLE", test_output_);
+  EXPECT_STREQ("APPLEBANANAPEAR", test_output_);
   delete log;
   LogTestHelper::FreeTestOutput();
 }
 
 }  // namespace dart