Add json fuzzer

test/fuzzer/json.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 <limits.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#include "include/v8.h"
+#include "test/fuzzer/fuzzer-support.h"
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
+  v8_fuzzer::FuzzerSupport* support = v8_fuzzer::FuzzerSupport::Get();
+  v8::Isolate* isolate = support->GetIsolate();
+
+  v8::Isolate::Scope isolate_scope(isolate);
+  v8::HandleScope handle_scope(isolate);
+  v8::Context::Scope context_scope(support->GetContext());
+  v8::TryCatch try_catch(isolate);
+
+  if (size > INT_MAX) return 0;
+  v8::Local<v8::String> source;
+  if (!v8::String::NewFromOneByte(isolate, data, v8::NewStringType::kNormal,
+                                  static_cast<int>(size))
+           .ToLocal(&source)) {
+    return 0;
+  }
+
+  v8::JSON::Parse(isolate, source).IsEmpty();
+  return 0;
+}