This moves the Hydrogen-specific {is_tracking_positions} predicate which
also depends on the --hydrogen-track-positions flag into the Crankshaft
directory and removes it from the more general {CompilationInfo}.

R=bmeurer@chromium.org

Review-Url: https://codereview.chromium.org/2377283002
Cr-Commit-Position: refs/heads/master@{#39913}