Don't reset handle before Wrappable is destroyed

It is possible that the user wants to use the V8 object in the destructor.

Fixes atom/atom-shell#1112.

native_mate/constructor.h

@@ -176,7 +176,7 @@ class Constructor {
   }
 
   base::StringPiece name_;
-  v8::Persistent<v8::FunctionTemplate> constructor_;
+  v8::UniquePersistent<v8::FunctionTemplate> constructor_;
 
   DISALLOW_COPY_AND_ASSIGN(Constructor);
 };

native_mate/constructor.h.pump

@@ -112,7 +112,7 @@ class Constructor {
   }
 
   base::StringPiece name_;
-  v8::Persistent<v8::FunctionTemplate> constructor_;
+  v8::UniquePersistent<v8::FunctionTemplate> constructor_;
 
   DISALLOW_COPY_AND_ASSIGN(Constructor);
 };

native_mate/function_template.h

@@ -57,7 +57,7 @@ class CallbackHolderBase {
  private:
   static MATE_WEAK_CALLBACK(WeakCallback, v8::External, CallbackHolderBase);
 
-  v8::Persistent<v8::External> v8_ref_;
+  v8::UniquePersistent<v8::External> v8_ref_;
 
   DISALLOW_COPY_AND_ASSIGN(CallbackHolderBase);
 };

native_mate/function_template.h.pump

@@ -60,7 +60,7 @@ class CallbackHolderBase {
  private:
   static MATE_WEAK_CALLBACK(WeakCallback, v8::External, CallbackHolderBase);
 
-  v8::Persistent<v8::External> v8_ref_;
+  v8::UniquePersistent<v8::External> v8_ref_;
 
   DISALLOW_COPY_AND_ASSIGN(CallbackHolderBase);
 };

native_mate/wrappable.cc

@@ -46,7 +46,6 @@ ObjectTemplateBuilder Wrappable::GetObjectTemplateBuilder(
 // static
 MATE_WEAK_CALLBACK(Wrappable::WeakCallback, v8::Object, Wrappable) {
   MATE_WEAK_CALLBACK_INIT(Wrappable);
-  MATE_PERSISTENT_RESET(self->wrapper_);
   delete self;
 }
 

native_mate/wrappable.h

@@ -74,7 +74,7 @@ class Wrappable {
  private:
   static MATE_WEAK_CALLBACK(WeakCallback, v8::Object, Wrappable);
 
-  v8::Persistent<v8::Object> wrapper_;  // Weak
+  v8::UniquePersistent<v8::Object> wrapper_;  // Weak
 
   DISALLOW_COPY_AND_ASSIGN(Wrappable);
 };