If exactly one byte in the upper half of the pushed 8-byte value is
set, use a smaller code sequence to push this value on the stack.
Before, we did
  movq r10,<constant>
  push r10
Now, we do
  push 0x0
  movb [rsp+<offset>],<byte>

The old sequence had 12 bytes, the new one has 7.
Pushing such values is used a lot for stack frame markers, which are
small numbers (1-17) encoded as SMIs.

Review-Url: https://codereview.chromium.org/2685213004
Cr-Commit-Position: refs/heads/master@{#43146}