[proxies] Implement [[PreventExtensions]] and [[IsExtensible]].

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index d30bda2ad3986abe8c6217f60ce1059e15e0c541..4a0696c6001a1549a04f776ae6dde30cc9734d86 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -9520,6 +9520,10 @@ class JSProxy: public JSReceiver {
   // ES6 9.5.1
   static MaybeHandle<Object> GetPrototype(Handle<JSProxy> receiver);
 
+  static bool IsRevoked(Handle<JSProxy> proxy);
+
+  MUST_USE_RESULT static Maybe<bool> IsExtensible(Handle<JSProxy> proxy);

[Camillo Bruni, 2015/11/17 08:57:17]

can you put the ES6 section? 9.5.?

+
   // ES6 9.5.5
   static bool GetOwnPropertyDescriptor(LookupIterator* it,
                                        PropertyDescriptor* desc);
@@ -9529,6 +9533,10 @@ class JSProxy: public JSReceiver {
       Handle<Object> receiver,
       Handle<Name> name);
 
+  // ES6 9.5.4 [[PreventExtensions]] (when passed DONT_THROW)
+  MUST_USE_RESULT static Maybe<bool> PreventExtensions(
+      Handle<JSProxy> proxy, ShouldThrow should_throw);
+
   // If the handler defines an accessor property with a setter, invoke it.
   // If it defines an accessor property without a setter, or a data property
   // that is read-only, fail.  In all these cases set '*done' to true.
@@ -9568,6 +9576,9 @@ class JSProxy: public JSReceiver {
  private:
   friend class JSReceiver;
 
+  MUST_USE_RESULT static MaybeHandle<Object> GetTrap(Handle<JSProxy> proxy,
+                                                     Handle<String> trap);
+
   // Invoke a trap by name. If the trap does not exist on this's handler,
   // but derived_trap is non-NULL, invoke that instead.  May cause GC.
   MUST_USE_RESULT static MaybeHandle<Object> CallTrap(