Make the fuchsia mojo/public repo the source of truth.

mojo/dart/packages/_mojo_for_test_only/lib/test/echo_service.mojom.dart

 // WARNING: DO NOT EDIT. This file was generated by a program.
 // See $MOJO_SDK/tools/bindings/mojom_bindings_generator.py.
 
 library echo_service_mojom;
 import 'dart:async';
 import 'dart:collection';
 import 'dart:convert';
 import 'dart:io';
 import 'dart:typed_data';
 import 'package:mojo/bindings.dart' as bindings;
@@ skipping 693 matching lines @@
 
 Map<String, mojom_types.UserDefinedType> getAllMojomTypeDefinitions() {
   return getRuntimeTypeInfo().typeMap;
 }
 
 var _runtimeTypeInfo;
 mojom_types.RuntimeTypeInfo  _initRuntimeTypeInfo() {
   // serializedRuntimeTypeInfo contains the bytes of the Mojo serialization of
   // a mojom_types.RuntimeTypeInfo struct describing the Mojom types in this
   // file. The string contains the base64 encoding of the gzip-compressed bytes.
-  var serializedRuntimeTypeInfo = "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";
+  var serializedRuntimeTypeInfo = "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";
 
   // Deserialize RuntimeTypeInfo
   var bytes = BASE64.decode(serializedRuntimeTypeInfo);
   var unzippedBytes = new ZLibDecoder().convert(bytes);
   var bdata = new ByteData.view(unzippedBytes.buffer);
   var message = new bindings.Message(bdata, null, unzippedBytes.length, 0);
   _runtimeTypeInfo = mojom_types.RuntimeTypeInfo.deserialize(message);
   return _runtimeTypeInfo;
 }