Show export numbers

Summary:
As discussed on an earlier diff, the percentage alone
is a confusing indicator as the number of items to be
serialised can grow over time, causing the percentage
to go down.

This shows the raw numbers in addition to the percentage.

Reviewed By: priteshrnandgaonkar

Differential Revision: D17762477

fbshipit-source-id: 8911b520b2ea74542bc64e6a6662bed7d4f81860

src/utils/serialization.tsx

@@ -196,7 +196,11 @@ export async function makeObjectSerializable(
       stack.length >= prevStackLength ? stack.length - prevStackLength + 1 : 0;
     const percentage = (numIterations / accumulator) * 100;
     statusUpdate &&
-      statusUpdate(`Serializing Flipper (${percentage.toFixed(2)}%) `);
+      statusUpdate(
+        `Serializing Flipper: ${numIterations} / ${accumulator} (${percentage.toFixed(
+          2,
+        )}%) `,
+      );
     prevStackLength = stack.length;
   }
   return dict.get(obj);