X87: [fullcodegen] Implement operand stack depth tracking.

  port 38915ed7 (r34211)

  original commit message:
  This implements a mechanism to track the exact depth of the operand
  stack in full-codegen for every sub-expression visitation. So far we
  only tracked the depth at statement level, but not at expression level.
  With the introduction of do-expressions it will be possible to construct
  local control flow (i.e. break, continue and friends) that target labels
  at an arbitrary operand stack depth, making this tracking a prerequisite
  for full do-expression support.

BUG=

Review URL: https://codereview.chromium.org/1728953003

Cr-Commit-Position: refs/heads/master@{#34231}