Implement function proxies (except for their use as constructors).

src/objects-debug.cc

Index: src/objects-debug.cc
diff --git a/src/objects-debug.cc b/src/objects-debug.cc
index 8c0330dae0de19a1075daaa959d2ab5835efe42d..78ecd33dfb3ffd302cf656c3415f80e8ab745f7c 100644
--- a/src/objects-debug.cc
+++ b/src/objects-debug.cc
@@ -164,6 +164,9 @@ void HeapObject::HeapObjectVerify() {
     case JS_PROXY_TYPE:
       JSProxy::cast(this)->JSProxyVerify();
       break;
+    case JS_FUNCTION_PROXY_TYPE:
+      JSFunctionProxy::cast(this)->JSFunctionProxyVerify();
+      break;
     case FOREIGN_TYPE:
       Foreign::cast(this)->ForeignVerify();
       break;
@@ -511,6 +514,15 @@ void JSProxy::JSProxyVerify() {
   VerifyPointer(handler());
 }
 
+
+void JSFunctionProxy::JSFunctionProxyVerify() {
+  ASSERT(IsJSFunctionProxy());
+  JSProxyVerify();
+  VerifyPointer(call_trap());
+  VerifyPointer(construct_trap());
+}
+
+
 void Foreign::ForeignVerify() {
   ASSERT(IsForeign());
 }