Code splits limitation

## Detailed Description

Since code split creates multiple independent chunks, prepack can only apply optimizations to chunk "shells", not modules contained in these chunks (maybe except for entry chunk).
I wondering if there is any workaround for this ?

## Possible Implementation

call `__optimize(module)` for each module in a chunk
eg: https://prepack.io/repl.html#GYVwdgxgLglg9mABAWzgExAGwKYEYAUAlIgN4BQiioksCVccRpFliATtlCG0gOTANeAbhYBfFtWjwkAIwCGbJuVbtO3PvLbCxLDlx71GxANSJNREeLIB9a3AAOsZDABe2fKgw5chMkA

No repository files or tests are identified in the issue. Start by reproducing the linked Prepack example and tracing how code-split chunks are handled; done means establishing whether each module in such a chunk can be passed to __optimize(module), including the stated entry-chunk exception.

Written by the indexing model from the issue text.