This extends pretenuring decisions based on allocation sites to heap
numbers that are allocated as part of object literals. It ensures memory
locality of a bigger enclosure of the deep copy of an object literal.

R=bmeurer@chromium.org
TEST=cctest/test-heap/OptimizedPretenuringMixedInObjectProperties

Review-Url: https://codereview.chromium.org/2135933002
Cr-Commit-Position: refs/heads/master@{#37645}