Add a library suitable for libfuzzer with a small unit test runner shell

test/fuzzer/parser.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 <stddef.h>
+#include <stdint.h>
+
+#include "include/v8.h"
+#include "src/objects.h"
+#include "src/parsing/parser.h"
+#include "src/parsing/preparser.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);
+
+  v8::internal::Isolate* i_isolate =
+      reinterpret_cast<v8::internal::Isolate*>(isolate);
+  v8::internal::Factory* factory = i_isolate->factory();
+
+  if (size > INT_MAX) return 0;
+  v8::internal::MaybeHandle<v8::internal::String> source =
+      factory->NewStringFromOneByte(
+          v8::internal::Vector<const uint8_t>(data, static_cast<int>(size)));
+  if (source.is_null()) return 0;
+
+  v8::internal::Handle<v8::internal::Script> script =
+      factory->NewScript(source.ToHandleChecked());
+  v8::internal::Zone zone;
+  v8::internal::ParseInfo info(&zone, script);
+  info.set_global();
+  v8::internal::Parser parser(&info);
+  parser.Parse(&info);
+  return 0;
+}