Get the OpenGLUI emulator building again on the desktop. Mostly this is applying the changes here:

runtime/embedders/openglui/common/extension.cc

 // Copyright (c) 2012, 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 "embedders/openglui/common/extension.h"
 
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ skipping 857 matching lines @@
     Dart_CObject* param1 = message->value.as_array.values[1];
     if (param0->type == Dart_CObject::kInt32 &&
         param1->type == Dart_CObject::kInt32) {
       int length = param0->value.as_int32;
       int seed = param1->value.as_int32;
 
       uint8_t* values = RandomArray(seed, length);
 
       if (values != NULL) {
         Dart_CObject result;
-        result.type = Dart_CObject::kUint8Array;
-        result.value.as_byte_array.values = values;
-        result.value.as_byte_array.length = length;
+        result.type = Dart_CObject::kTypedData;
+        result.value.as_typed_data.type = Dart_CObject::kUint8Array;
+        result.value.as_typed_data.values = values;
+        result.value.as_typed_data.length = length;
         Dart_PostCObject(reply_port_id, &result);
         free(values);
         // It is OK that result is destroyed when function exits.
         // Dart_PostCObject has copied its data.
         return;
       }
     }
   }
   Dart_CObject result;
   result.type = Dart_CObject::kNull;
@@ skipping 835 matching lines @@
   HandleError(Dart_StringToCString(name, &cname));
   for (int i = 0; function_list[i].name != NULL; ++i) {
     if (strcmp(function_list[i].name, cname) == 0) {
       result = function_list[i].function;
       break;
     }
   }
   Dart_ExitScope();
   return result;
 }