We were able to achieve our goals for register allocation independent of
the allocation algorithm. Performance data so far is inconclusive re. the
value of the Greedy algorithm, compared to the particular Linear Scan
implementation we're currently using, and the performance measurement
techniques we currently use are too imprecise to help with this matter.

Retiring the algorithm to lower maintenance and evolution cost (e.g. lower
cost of adding aliasing support). Once we improve benchmarking stability,
and establish a suite sensitive enough for codegen improvement studies,
we may revive the algorithm, should the need arise.

BUG=

Review-Url: https://codereview.chromium.org/2060673002
Cr-Commit-Position: refs/heads/master@{#36912}