Annex B 3.3 applies only for ordinary FunctionDeclarations, not
GeneratorDeclarations or AsyncFunctionDeclarations. This patch
- Skips applying Annex B 3.3 to async functions
- Adds a flag to refrain from applying it to generators
- UseCounter for how often duplicate function in block occurs
  with generators (unclear how to measure need for hoisting from block)

BUG=v8:4806

Review-Url: https://codereview.chromium.org/1995863002
Cr-Commit-Position: refs/heads/master@{#36557}