Port 659e8f7b

Original Commit Message:

    Instead of allocating and embedding certain heap numbers into the code
    during code assembly, emit dummies but record the allocation requests.
    Later then, in Assembler::GetCode, allocate the heap numbers and patch
    the code by replacing the dummies with the actual objects. The
    RelocInfos for the embedded objects are already recorded correctly when
    emitting the dummies.

R=neis@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, bjaideep@ca.ibm.com, michael_dawson@ca.ibm.com
BUG=v8:6048
LOG=N

Review-Url: https://codereview.chromium.org/2929843002
Cr-Commit-Position: refs/heads/master@{#45793}