[compiler] Put shared function marking behind a flag

src/flag-definitions.h

Index: src/flag-definitions.h
diff --git a/src/flag-definitions.h b/src/flag-definitions.h
index d6ad3c6f3b44815c0df69df44275449199a8d10b..1c6b25f924b4e08f64e56732f649380a6f28fa81 100644
--- a/src/flag-definitions.h
+++ b/src/flag-definitions.h
@@ -275,6 +275,8 @@ DEFINE_BOOL(track_field_types, true, "track field types")
 DEFINE_IMPLICATION(track_field_types, track_fields)
 DEFINE_IMPLICATION(track_field_types, track_heap_object_fields)
 DEFINE_BOOL(smi_binop, true, "support smi representation in binary operations")
+DEFINE_BOOL(mark_shared_functions, false,

[Michael Starzinger, 2016/10/25 10:38:24]

nit: The word "mark" is very much used for the GC marking, it makes it sound
like this flag is GC related. How would you feel about renaming this flag to
"FLAG_optimize_shared_functions" instead?

[Leszek Swirski, 2016/10/25 10:56:10]

Sure, done, though I may rename it again in the followup "tier up" CL  (to, say,
tier_up_shared_functions).

[Michael Starzinger, 2016/10/25 12:05:13]

Acknowledged. Yes, "tier up" also works for me. Totally up to you.

+            "mark shared functions for optimization")
 
 // Flags for optimization types.
 DEFINE_BOOL(optimize_for_size, false,