Update mojo sdk to rev 8d45c89c30b230843c5bd6dd0693a555750946c0

third_party/mojo/src/mojo/public/dart/src/message_pipe.dart

Index: third_party/mojo/src/mojo/public/dart/src/message_pipe.dart
diff --git a/third_party/mojo/src/mojo/public/dart/src/message_pipe.dart b/third_party/mojo/src/mojo/public/dart/src/message_pipe.dart
index 325be42f9371323ea24d03510d05c29dc2ee0340..7733d33a28a99ebf8388973bdcc9140c5730ce73 100644
--- a/third_party/mojo/src/mojo/public/dart/src/message_pipe.dart
+++ b/third_party/mojo/src/mojo/public/dart/src/message_pipe.dart
@@ -49,9 +49,11 @@ class MojoMessagePipeEndpoint {
       return status;
     }
 
+    int dataLengthInBytes = (data == null) ? 0 : data.lengthInBytes;
+
     // If numBytes has the default value, use the full length of the data.
-    int dataNumBytes = (numBytes == -1) ? data.lengthInBytes : numBytes;
-    if (dataNumBytes > data.lengthInBytes) {
+    int dataNumBytes = (numBytes == -1) ? dataLengthInBytes : numBytes;
+    if (dataNumBytes > dataLengthInBytes) {
       status = MojoResult.INVALID_ARGUMENT;
       return status;
     }