Replace Handle<> with Local in remaining gin/*

gin/public/context_holder.h

Index: gin/public/context_holder.h
diff --git a/gin/public/context_holder.h b/gin/public/context_holder.h
index b055b9680d421e8db36ad6fd0b9e0792c60151b0..835bffa2d3cd3ad9d8fa074d0e6ef1597ebde18c 100644
--- a/gin/public/context_holder.h
+++ b/gin/public/context_holder.h
@@ -33,11 +33,11 @@ class GIN_EXPORT ContextHolder {
 
   v8::Isolate* isolate() const { return isolate_; }
 
-  v8::Handle<v8::Context> context() const {
+  v8::Local<v8::Context> context() const {
     return v8::Local<v8::Context>::New(isolate_, context_);
   }
 
-  void SetContext(v8::Handle<v8::Context> context);
+  void SetContext(v8::Local<v8::Context> context);
 
  private:
   v8::Isolate* isolate_;