Create string efficiently from Uint16List/View.

runtime/vm/object.h

Index: runtime/vm/object.h
diff --git a/runtime/vm/object.h b/runtime/vm/object.h
index bbded409eb5196bbc44f0a0d4e6c0f68394182c3..90c3acf2acbe6e830d2fac0aece394b13d19d898 100644
--- a/runtime/vm/object.h
+++ b/runtime/vm/object.h
@@ -6177,6 +6177,16 @@ class TwoByteString : public AllStatic {
   static RawTwoByteString* New(const String& str,
                                Heap::Space space);
 
+  static RawTwoByteString* New(const TypedData& other_typed_data,
+                               intptr_t other_start_index,
+                               intptr_t other_len,
+                               Heap::Space space = Heap::kNew);
+
+  static RawTwoByteString* New(const ExternalTypedData& other_typed_data,
+                               intptr_t other_start_index,
+                               intptr_t other_len,
+                               Heap::Space space = Heap::kNew);
+
   static RawTwoByteString* Concat(const String& str1,
                                   const String& str2,
                                   Heap::Space space);