This removes the need to pass in the current unoptimized code when
requesting optimized code for a function. Note that the notion of
unoptimized code becomes moot when optimizing from the interpreter
bytecode, hence the API should not encode such a dependency.

R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/1588293005

Cr-Commit-Position: refs/heads/master@{#33353}