Fix MountingCoordinator override mode

Summary:
In MountingCoordinator override mode (used in LayoutAnimations) we must set the start and end `diff` time when no real diff happens, otherwise we will hit an assert in telemetry later.

I also ensure that the TransactionNumber is incremented in that case.

Changelog: [Internal]

Reviewed By: shergin

Differential Revision: D23746684

fbshipit-source-id: b1fe3864e453fdba89d43cc827bd37434abf7a4d

ReactCommon/react/renderer/mounting/MountingCoordinator.cpp

@@ -117,10 +117,13 @@ better::optional<MountingTransaction> MountingCoordinator::pullTransaction()
       mutations = transaction->getMutations();
       telemetry = transaction->getTelemetry();
     } else {
+      number_++;
       telemetry.willLayout();
       telemetry.didLayout();
       telemetry.willCommit();
       telemetry.didCommit();
+      telemetry.willDiff();
+      telemetry.didDiff();
     }
 
     transaction = mountingOverrideDelegate->pullTransaction(