The compiler patches all call sites with a default code object value.
We used to populate a vector with that value. Turns out that avoiding
having that vector measurably reduces instantiation time.

Bug: 
Change-Id: I2c843210a2ab24541f370b5493c3cbb555149e1a
Reviewed-on: https://chromium-review.googlesource.com/609480
Commit-Queue: Mircea Trofin <mtrofin@chromium.org>
Reviewed-by: Brad Nelson <bradnelson@chromium.org>
Reviewed-by: Ben Titzer <titzer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47296}