Split out libplatform into a separate libary

tools/lexer-shell.cc

Index: tools/lexer-shell.cc
diff --git a/tools/lexer-shell.cc b/tools/lexer-shell.cc
index 276a47315fe9b93ae29f383ef6e23821439ea225..ae3dbd2745d5a6bf7f0090eb4327fad4bd2d6f29 100644
--- a/tools/lexer-shell.cc
+++ b/tools/lexer-shell.cc
@@ -33,6 +33,7 @@
 #include <vector>
 #include "src/v8.h"
 
+#include "include/libplatform/libplatform.h"
 #include "src/api.h"
 #include "src/base/platform/platform.h"
 #include "src/messages.h"
@@ -180,6 +181,9 @@ v8::base::TimeDelta ProcessFile(
 
 int main(int argc, char* argv[]) {
   v8::V8::InitializeICU();
+  v8::Platform* platform = v8::platform::CreateDefaultPlatform(
+      v8::base::OS::NumberOfProcessorsOnline());
+  v8::V8::InitializePlatform(platform);
   v8::V8::SetFlagsFromCommandLine(&argc, argv, true);
   Encoding encoding = LATIN1;
   bool print_tokens = false;
@@ -226,5 +230,7 @@ int main(int argc, char* argv[]) {
     }
   }
   v8::V8::Dispose();
+  v8::V8::ShutdownPlatform();
+  delete platform;
   return 0;
 }