Remove infrastructure for experimental JS natives

src/heap/heap.h

Index: src/heap/heap.h
diff --git a/src/heap/heap.h b/src/heap/heap.h
index ad2623964fb1bf4c87804684c4664e20432c9773..9f82525cebccebf80aa17f642486eb538c08d99e 100644
--- a/src/heap/heap.h
+++ b/src/heap/heap.h
@@ -178,8 +178,6 @@ using v8::MemoryPressureLevel;
   V(Object, instanceof_cache_map, InstanceofCacheMap)                          \
   V(Object, instanceof_cache_answer, InstanceofCacheAnswer)                    \
   V(FixedArray, natives_source_cache, NativesSourceCache)                      \
-  V(FixedArray, experimental_natives_source_cache,                             \
-    ExperimentalNativesSourceCache)                                            \
   V(FixedArray, extra_natives_source_cache, ExtraNativesSourceCache)           \
   V(FixedArray, experimental_extra_natives_source_cache,                       \
     ExperimentalExtraNativesSourceCache)                                       \