Introduce safe interface to "copy and grow" FixedArray.

src/heap/heap.h

Index: src/heap/heap.h
diff --git a/src/heap/heap.h b/src/heap/heap.h
index 54dfc7ae1a26da7fb32d5f3922da73012a72102a..6d75879374cf72351a64d9da48716ccdcf27b39e 100644
--- a/src/heap/heap.h
+++ b/src/heap/heap.h
@@ -2019,17 +2019,18 @@ class Heap {
   // Allocates an uninitialized fixed array. It must be filled by the caller.
   MUST_USE_RESULT AllocationResult AllocateUninitializedFixedArray(int length);
 
-  // Make a copy of src and return it. Returns
-  // Failure::RetryAfterGC(requested_bytes, space) if the allocation failed.
+  // Make a copy of src and return it.
   MUST_USE_RESULT inline AllocationResult CopyFixedArray(FixedArray* src);
 
-  // Make a copy of src, set the map, and return the copy. Returns
-  // Failure::RetryAfterGC(requested_bytes, space) if the allocation failed.
+  // Make a copy of src, also grow the copy, and return the copy.
+  MUST_USE_RESULT AllocationResult
+      CopyFixedArrayAndGrow(FixedArray* src, int grow_by);
+
+  // Make a copy of src, set the map, and return the copy.
   MUST_USE_RESULT AllocationResult
       CopyFixedArrayWithMap(FixedArray* src, Map* map);
 
-  // Make a copy of src and return it. Returns
-  // Failure::RetryAfterGC(requested_bytes, space) if the allocation failed.
+  // Make a copy of src and return it.
   MUST_USE_RESULT inline AllocationResult CopyFixedDoubleArray(
       FixedDoubleArray* src);