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

mojo/dart/packages/_mojo_for_test_only/lib/mojo/examples/echo.mojom.dart

 // WARNING: DO NOT EDIT. This file was generated by a program.
 // See $MOJO_SDK/tools/bindings/mojom_bindings_generator.py.
 
 library echo_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 389 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;
 }