X87: Check that external references are registered in the serializer.

src/x87/macro-assembler-x87.cc

Index: src/x87/macro-assembler-x87.cc
diff --git a/src/x87/macro-assembler-x87.cc b/src/x87/macro-assembler-x87.cc
index 07f0fed0da33ad7c1eaec1825c9ea277432ec3b9..6196d8f7ae468ea2e65077818989e16f903729d6 100644
--- a/src/x87/macro-assembler-x87.cc
+++ b/src/x87/macro-assembler-x87.cc
@@ -3015,6 +3015,7 @@ void MacroAssembler::CheckPageFlagForMap(
     Label::Distance condition_met_distance) {
   DCHECK(cc == zero || cc == not_zero);
   Page* page = Page::FromAddress(map->address());
+  DCHECK(!serializer_enabled());  // Serializer cannot match page_flags.
   ExternalReference reference(ExternalReference::page_flags(page));
   // The inlined static address check of the page's flags relies
   // on maps never being compacted.