Make valgrind a bit more happy by zero-terminating/initializing strings.

src/compiler/graph-visualizer.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/graph-visualizer.h"
 
 #include <sstream>
 #include <string>
 
 #include "src/code-stubs.h"
 #include "src/compiler/all-nodes.h"
 #include "src/compiler/graph.h"
 #include "src/compiler/node.h"
 #include "src/compiler/node-properties.h"
 #include "src/compiler/opcodes.h"
 #include "src/compiler/operator.h"
 #include "src/compiler/operator-properties.h"
 #include "src/compiler/register-allocator.h"
 #include "src/compiler/schedule.h"
 #include "src/compiler/scheduler.h"
 #include "src/ostreams.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
 
 FILE* OpenVisualizerLogFile(CompilationInfo* info, const char* phase,
                             const char* suffix, const char* mode) {
-  EmbeddedVector<char, 256> filename;
+  EmbeddedVector<char, 256> filename(0);
   SmartArrayPointer<char> function_name;
-  if (!info->shared_info().is_null()) {
+  if (info->has_shared_info()) {
     function_name = info->shared_info()->DebugName()->ToCString();
     if (strlen(function_name.get()) > 0) {
       SNPrintF(filename, "turbo-%s", function_name.get());
     } else {
       SNPrintF(filename, "turbo-%p", static_cast<void*>(info));
     }
   } else {
     SNPrintF(filename, "turbo-none-%s", phase);
   }
   std::replace(filename.start(), filename.start() + filename.length(), ' ',
@@ skipping 772 matching lines @@
         os << "#" << SafeId(i) << ":" << SafeMnemonic(i);
       }
       os << ")" << std::endl;
     }
   }
   return os;
 }
 }
 }
 }  // namespace v8::internal::compiler