[runtime/heap] Introduce CopyFixedArrayUpTo to match CopyFixedArrayAndGrow, copying to a smaller ar…

src/factory.h

Index: src/factory.h
diff --git a/src/factory.h b/src/factory.h
index 70653f5943367efebe3ea5003b029bbec200406f..fbc92222da71301df89b08e3fa076ce43c39de62 100644
--- a/src/factory.h
+++ b/src/factory.h
@@ -323,6 +323,9 @@ class Factory final {
       Handle<FixedArray> array, int grow_by,
       PretenureFlag pretenure = NOT_TENURED);
 
+  Handle<FixedArray> CopyFixedArrayUpTo(Handle<FixedArray> array, int new_len,
+                                        PretenureFlag pretenure = NOT_TENURED);
+
   Handle<FixedArray> CopyFixedArray(Handle<FixedArray> array);
 
   // This method expects a COW array in new space, and creates a copy