Treat pointers in optimized code as strong before all weak dependencies are registered.

Treat pointers in optimized code as strong before all weak dependencies are registered.

This prevents GC from observing code objects with out-of-sync weak dependencies.

BUG=v8:3823
LOG=N

Review URL: https://codereview.chromium.org/866723002

Cr-Commit-Position: refs/heads/master@{#26225}