Implement core support for FixedDoubleArrays.

src/heap.h

Index: src/heap.h
diff --git a/src/heap.h b/src/heap.h
index f97344b81d856b8a7438cbc23362c62429703017..664cce867dcf500dd0c00c84ba6095d02646b5be 100644
--- a/src/heap.h
+++ b/src/heap.h
@@ -66,6 +66,7 @@ inline Heap* _inline_get_heap_();
   V(Map, global_context_map, GlobalContextMap)                                 \
   V(Map, fixed_array_map, FixedArrayMap)                                       \
   V(Map, fixed_cow_array_map, FixedCOWArrayMap)                                \
+  V(Map, fixed_double_array_map, FixedDoubleArrayMap)                          \
   V(Object, no_interceptor_result_sentinel, NoInterceptorResultSentinel)       \
   V(Map, meta_map, MetaMap)                                                    \
   V(Map, hash_table_map, HashTableMap)                                         \
@@ -78,6 +79,7 @@ inline Heap* _inline_get_heap_();
   V(Object, termination_exception, TerminationException)                       \
   V(FixedArray, empty_fixed_array, EmptyFixedArray)                            \
   V(ByteArray, empty_byte_array, EmptyByteArray)                               \
+  V(FixedDoubleArray, empty_fixed_double_array, EmptyFixedDoubleArray)         \
   V(String, empty_string, EmptyString)                                         \
   V(DescriptorArray, empty_descriptor_array, EmptyDescriptorArray)             \
   V(Map, string_map, StringMap)                                                \
@@ -620,6 +622,17 @@ class Heap {
       int length,
       PretenureFlag pretenure = NOT_TENURED);
 
+  MUST_USE_RESULT MaybeObject* AllocateRawFixedDoubleArray(
+      int length,
+      PretenureFlag pretenure);
+
+  // Allocates a fixed double array with uninitialized values. Returns
+  // Failure::RetryAfterGC(requested_bytes, space) if the allocation failed.
+  // Please note this does not perform a garbage collection.
+  MUST_USE_RESULT MaybeObject* AllocateUninitializedFixedDoubleArray(
+      int length,
+      PretenureFlag pretenure = NOT_TENURED);
+
   // AllocateHashTable is identical to AllocateFixedArray except
   // that the resulting object has hash_table_map as map.
   MUST_USE_RESULT MaybeObject* AllocateHashTable(
@@ -1460,6 +1473,9 @@ class Heap {
   // Allocate empty fixed array.
   MUST_USE_RESULT MaybeObject* AllocateEmptyFixedArray();
 
+  // Allocate empty fixed double array.
+  MUST_USE_RESULT MaybeObject* AllocateEmptyFixedDoubleArray();
+
   void SwitchScavengingVisitorsTableIfProfilingWasEnabled();
 
   // Performs a minor collection in new generation.