When WebAssembly.Table initial size is greater than the declared initial size, table size references should be updated on instantiate for functions to be called at indices greater than the declared initial size.

R=bradnelson@chromium.org, titzer@chromium.org

Review-Url: https://codereview.chromium.org/2661773002
Cr-Commit-Position: refs/heads/master@{#42781}