Reduce the number of dynamic calls.

lib/src/protobuf/generated_message.dart

Index: lib/src/protobuf/generated_message.dart
diff --git a/lib/src/protobuf/generated_message.dart b/lib/src/protobuf/generated_message.dart
index 8e076128a05836ec73b3822a264a0fd64e34503f..ef513c0076590a013cec813a7b29b37a1d1978df 100644
--- a/lib/src/protobuf/generated_message.dart
+++ b/lib/src/protobuf/generated_message.dart
@@ -67,10 +67,8 @@ abstract class GeneratedMessage {
   // TODO(antonm): move to getters.
   int getTagNumber(String fieldName) => info_.tagNumber(fieldName);
 
-  bool operator ==(other) {
-    if (other is! GeneratedMessage) return false;
-    return _fieldSet._equals(other._fieldSet);
-  }
+  bool operator ==(other) =>
+      other is GeneratedMessage ? _fieldSet._equals(other._fieldSet) : false;
 
   /// Calculates a hash code based on the contents of the protobuf.
   ///