[proxies] Expose proxies in the API

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 548d93b8447446e9d187dd81574ea854a64c6381..edc9d42a97bcb7fc0f4bb55430bcbc2315f144f8 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -9518,6 +9518,10 @@ class WeakCell : public HeapObject {
 // The JSProxy describes EcmaScript Harmony proxies
 class JSProxy: public JSReceiver {
  public:
+  MUST_USE_RESULT static MaybeHandle<JSProxy> New(Isolate* isolate,
+                                                  Handle<Object>,
+                                                  Handle<Object>);
+
   // [handler]: The handler property.
   DECL_ACCESSORS(handler, Object)
   // [target]: The target property.