Update Dart bindings for _mojo_for_test_only package.

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

Index: mojo/dart/packages/_mojo_for_test_only/lib/test/echo_service.mojom.dart
diff --git a/mojo/dart/packages/_mojo_for_test_only/lib/test/echo_service.mojom.dart b/mojo/dart/packages/_mojo_for_test_only/lib/test/echo_service.mojom.dart
index 42917384e71681f5ff13176cf128285371f16969..7e91ad3fee396d2fd3861fccba3a76633df62f82 100644
--- a/mojo/dart/packages/_mojo_for_test_only/lib/test/echo_service.mojom.dart
+++ b/mojo/dart/packages/_mojo_for_test_only/lib/test/echo_service.mojom.dart
@@ -694,7 +694,7 @@ 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);