Add output operator to VectorSlotPair

Bug: v8:7127
Change-Id: Ibdbf6c5627f3fe8a29ae44cc0c284896c344a0ae
Reviewed-on: https://chromium-review.googlesource.com/817295
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49967}

src/vector-slot-pair.cc

@@ -24,6 +24,14 @@ bool operator!=(VectorSlotPair const& lhs, VectorSlotPair const& rhs) {
   return !(lhs == rhs);
 }
 
+std::ostream& operator<<(std::ostream& os, const VectorSlotPair& pair) {
+  if (pair.IsValid()) {
+    return os << "VectorSlotPair(" << pair.vector().address() << pair.slot()
+              << ")";
+  }
+  return os << "VectorSlotPair(INVALID)";
+}
+
 size_t hash_value(VectorSlotPair const& p) {
   return base::hash_combine(p.slot(), p.vector().location());
 }

src/vector-slot-pair.h

@@ -37,6 +37,8 @@ class V8_EXPORT_PRIVATE VectorSlotPair {
 bool operator==(VectorSlotPair const&, VectorSlotPair const&);
 bool operator!=(VectorSlotPair const&, VectorSlotPair const&);
 
+std::ostream& operator<<(std::ostream& os, const VectorSlotPair& pair);
+
 size_t hash_value(VectorSlotPair const&);
 
 }  // namespace internal