title: Flutter app crashes when it use Firestore plugin in Release mode
body: <p>Everything works perfectly when in debug mode. It first happened when I update Flutter version to 1.10.x I could not remember which version did I use, properly. It should be 1.7.8, it was stable. To fix it I downgrade the flutter to 1.7.8+4 and also downgrade firebase related pub packages. But error still here.</p>
  
  <p>Stack Trace for Related Error, captured from gogle play console</p>
  
  <pre><code>java.lang.RuntimeException: 
    at com.google.firebase.firestore.util.AsyncQueue.a (AsyncQueue.java:379)
    at com.google.firebase.firestore.util.AsyncQueue$$Lambda$5.run (AsyncQueue.java:2)
    at android.os.Handler.handleCallback (Handler.java:790)
    at android.os.Handler.dispatchMessage (Handler.java:99)
    at android.os.Looper.loop (Looper.java:164)
    at android.app.ActivityThread.main (ActivityThread.java:7000)
    at java.lang.reflect.Method.invoke (Method.java)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run (RuntimeInit.java:441)
    at com.android.internal.os.ZygoteInit.main (ZygoteInit.java:1408)
  Caused by: java.lang.AbstractMethodError: 
    at com.google.protobuf.GeneratedMessageLite.a (GeneratedMessageLite.java:1319)
    at com.google.firebase.firestore.proto.WriteBatch.s (WriteBatch.java:120)
    at com.google.firebase.firestore.proto.WriteBatch.a (WriteBatch.java:162)
    at com.google.firebase.firestore.proto.WriteBatch.a (WriteBatch.java:15)
    at com.google.firebase.firestore.proto.WriteBatch$Builder.a (WriteBatch.java:835)
    at com.google.firebase.firestore.local.LocalSerializer.a (LocalSerializer.java:172)
    at com.google.firebase.firestore.local.SQLiteMutationQueue.a (SQLiteMutationQueue.java:188)
    at com.google.firebase.firestore.local.LocalStore.a (LocalStore.java:237)
    at com.google.firebase.firestore.local.LocalStore$$Lambda$2.get (LocalStore.java:8)
    at com.google.firebase.firestore.local.SQLitePersistence.a (SQLitePersistence.java:195)
    at com.google.firebase.firestore.local.LocalStore.a (LocalStore.java:201)
    at com.google.firebase.firestore.core.SyncEngine.a (SyncEngine.java:227)
    at com.google.firebase.firestore.core.FirestoreClient.a (FirestoreClient.java:200)
    at com.google.firebase.firestore.core.FirestoreClient$$Lambda$11.run (FirestoreClient.java:6)
    at com.google.firebase.firestore.util.AsyncQueue.a (AsyncQueue.java:311)
    at com.google.firebase.firestore.util.AsyncQueue$$Lambda$4.call (AsyncQueue.java:2)
    at com.google.firebase.firestore.util.AsyncQueue.a (AsyncQueue.java:287)
    at com.google.firebase.firestore.util.AsyncQueue$$Lambda$3.run (AsyncQueue.java:4)
    at java.util.concurrent.Executors$RunnableAdapter.call (Executors.java:457)
    at java.util.concurrent.FutureTask.run (FutureTask.java:266)
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run             
  (ScheduledThreadPoolExecutor.java:301)
    at java.util.concurrent.ThreadPoolExecutor.runWorker (ThreadPoolExecutor.java:1162)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run (ThreadPoolExecutor.java:636)
    at com.google.firebase.firestore.util.AsyncQueue$DelayedStartFactory.run (AsyncQueue.java:205)
    at java.lang.Thread.run (Thread.java:764)
  </code></pre>
  
  <p>When I saw the error trace on device (in android crash report dialog) It mentioned Firebase 19.0.0</p>
  
  <p>Flutter Doctor:</p>
  
  <pre><code>Doctor summary (to see all details, run flutter doctor -v):
  [√] Flutter (Channel unknown, v1.7.8+hotfix.4, on Microsoft Windows [Version 10.0.17134.1069], locale en-US)
  
  [√] Android toolchain - develop for Android devices (Android SDK version 29.0.0)
  [√] Chrome - develop for the web
  [√] Visual Studio - develop for Windows (Visual Studio Enterprise 2017 15.9.7)
  [√] Android Studio (version 3.4)
  [√] VS Code, 64-bit edition (version 1.38.1)
  [√] Connected device (3 available)
  
  • No issues found!
  </code></pre>
  
  <p>Error reporoducing scenario for final describe:</p>
  
  <ul>
  <li>Build app with <code>flutter run --release</code></li>
  <li>App try an basic firestore call
  
  <blockquote>
    <p>Firestore.instance.collection('collection-name').document('docuemnt-id').get()</p>
  </blockquote></li>
  <li>App crashes.</li>
  </ul>
  
  <p>Also getting the same error with building with <code>flutter build appbudle</code></p>