[generators] Create the fixed array holding the registers only once.

src/heap/heap.h

Index: src/heap/heap.h
diff --git a/src/heap/heap.h b/src/heap/heap.h
index b29eeb44bc1e28a1061b524727334566e081320c..3e0f10a491e03f9464f0f9237cddf0c515612dfc 100644
--- a/src/heap/heap.h
+++ b/src/heap/heap.h
@@ -78,6 +78,7 @@ using v8::MemoryPressureLevel;
   V(Oddball, exception, Exception)                                             \
   V(Oddball, termination_exception, TerminationException)                      \
   V(Oddball, optimized_out, OptimizedOut)                                      \
+  V(Oddball, placeholder, Placeholder)                                         \
   V(FixedArray, number_string_cache, NumberStringCache)                        \
   V(Object, instanceof_cache_function, InstanceofCacheFunction)                \
   V(Object, instanceof_cache_map, InstanceofCacheMap)                          \
@@ -152,6 +153,7 @@ using v8::MemoryPressureLevel;
   V(Map, exception_map, ExceptionMap)                                          \
   V(Map, termination_exception_map, TerminationExceptionMap)                   \
   V(Map, optimized_out_map, OptimizedOutMap)                                   \
+  V(Map, placeholder_map, PlaceholderMap)                                      \
   V(Map, message_object_map, JSMessageObjectMap)                               \
   V(Map, foreign_map, ForeignMap)                                              \
   V(Map, neander_map, NeanderMap)                                              \