Define a flag --future to enable the most probable future shipping config

That way we don't have to update the perf tests whenever the exact
configuration changes.

R=mvstanton@chromium.org,hablich@chromium.org,danno@chromium.org
BUG=

Review-Url: https://codereview.chromium.org/2420053002
Cr-Commit-Position: refs/heads/master@{#40944}

src/flag-definitions.h

@@ -248,6 +248,11 @@ HARMONY_STAGED(FLAG_STAGED_FEATURES)
 HARMONY_SHIPPING(FLAG_SHIPPING_FEATURES)
 #undef FLAG_SHIPPING_FEATURES
 
+DEFINE_BOOL(future, false,
+            "Implies all staged features that we want to ship in the "
+            "not-too-far future")
+DEFINE_IMPLICATION(future, ignition_staging)
+
 // Flags for experimental implementation features.
 DEFINE_BOOL(allocation_site_pretenuring, true,
             "pretenure with allocation sites")