Set V8 extras mode in gin::V8Initializer.

gin/isolate_holder.cc

Index: gin/isolate_holder.cc
diff --git a/gin/isolate_holder.cc b/gin/isolate_holder.cc
index 3defd7ce9b5d080855302e3a1356b91f6049e521..59d6f06c07a9e5eefa87edc76f0961d1ab5559dd 100644
--- a/gin/isolate_holder.cc
+++ b/gin/isolate_holder.cc
@@ -74,9 +74,10 @@ IsolateHolder::~IsolateHolder() {
 
 // static
 void IsolateHolder::Initialize(ScriptMode mode,
+                               V8ExtrasMode v8_extras_mode,
                                v8::ArrayBuffer::Allocator* allocator) {
   CHECK(allocator);
-  V8Initializer::Initialize(mode);
+  V8Initializer::Initialize(mode, v8_extras_mode);
   g_array_buffer_allocator = allocator;
 }