[Tracing] Create TraceConfig JSON string parser in D8.

src/d8.h

 // Copyright 2012 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.
 
 #ifndef V8_D8_H_
 #define V8_D8_H_
 
 #ifndef V8_SHARED
 #include "src/allocation.h"
 #include "src/base/hashmap.h"
@@ skipping 273 matching lines @@
         test_shell(false),
         dump_heap_constants(false),
         expected_to_throw(false),
         mock_arraybuffer_allocator(false),
         num_isolates(1),
         compile_options(v8::ScriptCompiler::kNoCompileOptions),
         isolate_sources(NULL),
         icu_data_file(NULL),
         natives_blob(NULL),
         snapshot_blob(NULL),
-        trace_enabled(false) {}
+        trace_enabled(false),
+        trace_config(NULL) {}
 
   ~ShellOptions() {
     delete[] isolate_sources;
   }
 
   bool use_interactive_shell() {
     return (interactive_shell || !script_executed) && !test_shell;
   }
 
   bool script_executed;
@@ skipping 171 matching lines @@
   static Local<ObjectTemplate> CreateGlobalTemplate(Isolate* isolate);
   static MaybeLocal<Context> CreateRealm(
       const v8::FunctionCallbackInfo<v8::Value>& args);
 };
 
 
 }  // namespace v8
 
 
 #endif  // V8_D8_H_