Generated dart code should import transitive imports.

mojo/dart/packages/_mojo_for_test_only/lib/imported/sample_import.mojom.dart

Index: mojo/dart/packages/_mojo_for_test_only/lib/imported/sample_import.mojom.dart
diff --git a/mojo/dart/packages/_mojo_for_test_only/lib/imported/sample_import.mojom.dart b/mojo/dart/packages/_mojo_for_test_only/lib/imported/sample_import.mojom.dart
index 9a6ee9151ad32b3df688465c7a7a7315b4b88d0f..a308282bc739bfc35909a495d66bc3debf8db0bd 100644
--- a/mojo/dart/packages/_mojo_for_test_only/lib/imported/sample_import.mojom.dart
+++ b/mojo/dart/packages/_mojo_for_test_only/lib/imported/sample_import.mojom.dart
@@ -542,7 +542,7 @@ 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);