Refactor IsolateHolder to be able to always create the isolate

gin/shell/gin_main.cc

Index: gin/shell/gin_main.cc
diff --git a/gin/shell/gin_main.cc b/gin/shell/gin_main.cc
index c8e3784b42df29af44a041d703df47342aee83b2..aa9f2b5ea93625067949cad9f40847da0d0caa72 100644
--- a/gin/shell/gin_main.cc
+++ b/gin/shell/gin_main.cc
@@ -8,6 +8,7 @@
 #include "base/files/file_util.h"
 #include "base/i18n/icu_util.h"
 #include "base/message_loop/message_loop.h"
+#include "gin/array_buffer.h"
 #include "gin/modules/console.h"
 #include "gin/modules/module_runner_delegate.h"
 #include "gin/public/isolate_holder.h"
@@ -61,7 +62,9 @@ int main(int argc, char** argv) {
   CommandLine::Init(argc, argv);
   base::i18n::InitializeICU();
 
-  gin::IsolateHolder instance(gin::IsolateHolder::kStrictMode);
+  gin::IsolateHolder::Initialize(gin::IsolateHolder::kStrictMode,
+                                 gin::ArrayBufferAllocator::SharedInstance());
+  gin::IsolateHolder instance;
 
   base::MessageLoop message_loop;