- Move the CompilationDependencies member of OptimizedCompilationInfo
  to Turbofan's PipelineData (and thus into the compiler namespace).
- Move compilation-dependencies.{cc,h} to the compiler directory.

Bug: v8:7902
Change-Id: I5471d0923daf83abe975357325db5bc5ad0a8571
Reviewed-on: https://chromium-review.googlesource.com/1127793
Commit-Queue: Georg Neis <neis@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54295}