[inspector] fixed console.count with empty stack

src/inspector/v8-console.cc

 // Copyright 2016 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/inspector/v8-console.h"
 
 #include "src/base/macros.h"
 #include "src/inspector/injected-script.h"
 #include "src/inspector/inspected-context.h"
 #include "src/inspector/string-util.h"
@@ skipping 326 matching lines @@
 }
 
 void V8Console::countCallback(const v8::FunctionCallbackInfo<v8::Value>& info) {
   ConsoleHelper helper(info);
 
   String16 title = helper.firstArgToString(String16());
   String16 identifier;
   if (title.isEmpty()) {
     std::unique_ptr<V8StackTraceImpl> stackTrace =
         V8StackTraceImpl::capture(nullptr, 0, 1);
-    if (stackTrace)
+    if (stackTrace && !stackTrace->isEmpty()) {
       identifier = toString16(stackTrace->topSourceURL()) + ":" +
                    String16::fromInteger(stackTrace->topLineNumber());
+    }
   } else {
     identifier = title + "@";
   }
 
   v8::Local<v8::Map> countMap;
   if (!helper.privateMap("V8Console#countMap").ToLocal(&countMap)) return;
   int32_t count = helper.getIntFromMap(countMap, identifier, 0) + 1;
   helper.setIntOnMap(countMap, identifier, count);
   helper.reportCallWithArgument(ConsoleAPIType::kCount,
                                 title + ": " + String16::fromInteger(count));
@@ skipping 548 matching lines @@
                          ->GetOwnPropertyDescriptor(
                              m_context, v8::Local<v8::String>::Cast(name))
                          .ToLocal(&descriptor);
       DCHECK(success);
       USE(success);
     }
   }
 }
 
 }  // namespace v8_inspector