Provide baseline for experimental GC implementation.

src/spaces-inl.h

Index: src/spaces-inl.h
diff --git a/src/spaces-inl.h b/src/spaces-inl.h
index aaca9e45caa49617ac9d35adf7e6f5f8df17bb81..17a381798ccd38c21c94d9377ebd9bcd9db74b8f 100644
--- a/src/spaces-inl.h
+++ b/src/spaces-inl.h
@@ -114,12 +114,18 @@ Address Page::CachedAllocationWatermark() {
 
 
 uint32_t Page::GetRegionMarks() {
+#ifdef ENABLE_CARDMARKING_WRITE_BARRIER
   return dirty_regions_;
+#else
+  return kAllRegionsDirtyMarks;
+#endif
 }
 
 
 void Page::SetRegionMarks(uint32_t marks) {
+#ifdef ENABLE_CARDMARKING_WRITE_BARRIER
   dirty_regions_ = marks;
+#endif
 }