Introduce a new AccessorPair type for handling JavaScript accessors.

src/objects-debug.cc

Index: src/objects-debug.cc
diff --git a/src/objects-debug.cc b/src/objects-debug.cc
index 64bda9473f6ca4d98232046094c5faf560d0f97e..eddfb93be2db80ef078637eb5c62fc9848de16d1 100644
--- a/src/objects-debug.cc
+++ b/src/objects-debug.cc
@@ -602,6 +602,13 @@ void AccessorInfo::AccessorInfoVerify() {
 }
 
 
+void AccessorPair::AccessorPairVerify() {
+  CHECK(IsAccessorPair());
+  VerifyPointer(getter());
+  VerifyPointer(setter());
+}
+
+
 void AccessCheckInfo::AccessCheckInfoVerify() {
   CHECK(IsAccessCheckInfo());
   VerifyPointer(named_callback());