Ensure that the worker pool is running if we intend to use it

src/libplatform/default-platform.h

Index: src/libplatform/default-platform.h
diff --git a/src/libplatform/default-platform.h b/src/libplatform/default-platform.h
index 877b3a63e7b23e5882face165b5f393e27867800..5c488323442272a72c959db728e9a41e63e96014 100644
--- a/src/libplatform/default-platform.h
+++ b/src/libplatform/default-platform.h
@@ -50,6 +50,8 @@ class DefaultPlatform : public Platform {
 
   void SetThreadPoolSize(int thread_pool_size);
 
+  void EnsureInitialized();
+
   // v8::Platform implementation.
   virtual void CallOnBackgroundThread(
       Task *task, ExpectedRuntime expected_runtime) V8_OVERRIDE;
@@ -59,8 +61,6 @@ class DefaultPlatform : public Platform {
  private:
   static const int kMaxThreadPoolSize = 4;
 
-  void EnsureInitialized();
-
   Mutex lock_;
   bool initialized_;
   int thread_pool_size_;