[proxies] Improve JSProxyVerify and test most proxy invariants.

src/objects-debug.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/objects.h"
 
 #include "src/bootstrapper.h"
 #include "src/disasm.h"
 #include "src/disassembler.h"
 #include "src/macro-assembler.h"
@@ skipping 800 matching lines @@
     default:
       CHECK_EQ(JSRegExp::NOT_COMPILED, TypeTag());
       CHECK(data()->IsUndefined());
       break;
   }
 }
 
 
 void JSProxy::JSProxyVerify() {
   CHECK(IsJSProxy());
+  VerifyPointer(target());
   VerifyPointer(handler());
+  CHECK_EQ(target()->IsCallable(), map()->is_callable());
+  CHECK_EQ(target()->IsConstructor(), map()->is_constructor());
   CHECK(hash()->IsSmi() || hash()->IsUndefined());
+  CHECK(map()->prototype()->IsNull());
+  // There should be no properties on a Proxy.
+  CHECK_EQ(0, map()->NumberOfOwnDescriptors());
 }
 
 
 void JSArrayBuffer::JSArrayBufferVerify() {
   CHECK(IsJSArrayBuffer());
   JSObjectVerify();
   VerifyPointer(byte_length());
   CHECK(byte_length()->IsSmi() || byte_length()->IsHeapNumber()
         || byte_length()->IsUndefined());
 }
@@ skipping 477 matching lines @@
 
   // Both are done at the same time.
   CHECK_EQ(new_it.done(), old_it.done());
 }
 
 
 #endif  // DEBUG
 
 }  // namespace internal
 }  // namespace v8