Fix memory-issue String::fromCharCodes, where a GC could invalidate an address.

runtime/vm/object.h

Index: runtime/vm/object.h
diff --git a/runtime/vm/object.h b/runtime/vm/object.h
index 6c71efdcb071cdfe28f7907b71412807a0357cd3..0789c0e3c1d812a102af3864f812e26df9ca46a2 100644
--- a/runtime/vm/object.h
+++ b/runtime/vm/object.h
@@ -5306,6 +5306,16 @@ class OneByteString : public AllStatic {
                                intptr_t other_len,
                                Heap::Space space);
 
+  static RawOneByteString* New(const TypedData& other_typed_data,
+                               intptr_t other_start_index,
+                               intptr_t other_len,
+                               Heap::Space space = Heap::kNew);
+
+  static RawOneByteString* New(const ExternalTypedData& other_typed_data,
+                               intptr_t other_start_index,
+                               intptr_t other_len,
+                               Heap::Space space = Heap::kNew);
+
   static RawOneByteString* Concat(const String& str1,
                                   const String& str2,
                                   Heap::Space space);