Narrow String::CharAt from int32_t to uint16_t.

runtime/vm/dart_api_impl.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "include/dart_api.h"
 #include "include/dart_mirrors_api.h"
 #include "include/dart_native_api.h"
 
 #include "platform/assert.h"
 #include "vm/class_finalizer.h"
@@ skipping 2288 matching lines @@
                                            intptr_t* length) {
   Isolate* isolate = Isolate::Current();
   DARTSCOPE(isolate);
   const String& str_obj = Api::UnwrapStringHandle(isolate, str);
   if (str_obj.IsNull()) {
     RETURN_TYPE_ERROR(isolate, str, String);
   }
   intptr_t str_len = str_obj.Length();
   intptr_t copy_len = (str_len > *length) ? *length : str_len;
   for (intptr_t i = 0; i < copy_len; i++) {
-    utf16_array[i] = static_cast<uint16_t>(str_obj.CharAt(i));
+    utf16_array[i] = str_obj.CharAt(i);
   }
   *length = copy_len;
   return Api::Success();
 }
 
 
 DART_EXPORT Dart_Handle Dart_StringStorageSize(Dart_Handle str,
                                                intptr_t* size) {
   Isolate* isolate = Isolate::Current();
   CHECK_ISOLATE(isolate);
@@ skipping 46 matching lines @@
       uint8_t* latin1_array = reinterpret_cast<uint8_t*>(array);
       for (intptr_t i = 0; i < copy_len; i++) {
         latin1_array[i] = static_cast<uint8_t>(str_obj.CharAt(i));
       }
       OneByteString::SetPeer(str_obj, peer, cback);
     } else {
       ASSERT(str_obj.IsTwoByteString());
       ASSERT(length >= (copy_len * str_obj.CharSize()));
       uint16_t* utf16_array = reinterpret_cast<uint16_t*>(array);
       for (intptr_t i = 0; i < copy_len; i++) {
-        utf16_array[i] = static_cast<uint16_t>(str_obj.CharAt(i));
+        utf16_array[i] = str_obj.CharAt(i);
       }
       TwoByteString::SetPeer(str_obj, peer, cback);
     }
     return str;
   }
   return Api::NewHandle(isolate,
                         str_obj.MakeExternal(array, length, peer, cback));
 }
 
 
@@ skipping 2997 matching lines @@
 
 
 DART_EXPORT void Dart_RegisterRootServiceRequestCallback(
     const char* name,
     Dart_ServiceRequestCallback callback,
     void* user_data) {
   Service::RegisterRootEmbedderCallback(name, callback, user_data);
 }
 
 }  // namespace dart