Provide baseline GC version.

src/spaces.cc

Index: src/spaces.cc
diff --git a/src/spaces.cc b/src/spaces.cc
index cdc682f879bf5e9bce8b9bf173ab32485f89b70b..a6ad3137197ab6d8fb7ae4760da2ece1f6adbbc2 100644
--- a/src/spaces.cc
+++ b/src/spaces.cc
@@ -2782,6 +2782,7 @@ void MapSpace::PrepareForMarkCompact(bool will_compact) {
   // Call prepare of the super class.
   FixedSpace::PrepareForMarkCompact(will_compact);
 
+#ifndef BASELINE_GC
   if (will_compact) {
     // Initialize map index entry.
     int page_count = 0;
@@ -2795,6 +2796,7 @@ void MapSpace::PrepareForMarkCompact(bool will_compact) {
       page_addresses_[page_count++] = p->address();
     }
   }
+#endif
 }