Add -optimize-for-size flag to optimize for memory size

src/flag-definitions.h

Index: src/flag-definitions.h
diff --git a/src/flag-definitions.h b/src/flag-definitions.h
index e734c7d3c6429bce47455261a1bb36cec37dcafd..fcc3f721b0724778c798b44fa2a0cf8694eee1ce 100644
--- a/src/flag-definitions.h
+++ b/src/flag-definitions.h
@@ -222,6 +222,10 @@ DEFINE_implication(track_heap_object_fields, track_fields)
 DEFINE_implication(track_computed_fields, track_fields)
 DEFINE_bool(smi_binop, true, "support smi representation in binary operations")
 
+// Flags for optimization types.
+DEFINE_bool(Os, false, "Optimize for size. Enables optimizations which reduce "

[Hannes Payer (out of office), 2013/09/23 11:38:43]

I just talked to danno: --optimize-for-size is a better name, --Os is to
cryptic.
Moreover, can you make the description generic? This mode should in the future
turn on all kinds of size specific optimizations. And the description should say
that it favors memory size over execution speed.

[rmcilroy, 2013/09/23 12:40:15]

Done.

+            "generated code size.")
+
 // Flags for data representation optimizations
 DEFINE_bool(unbox_double_arrays, true, "automatically unbox arrays of doubles")
 DEFINE_bool(string_slices, true, "use string slices")
@@ -594,9 +598,6 @@ DEFINE_int(hash_seed,
            0,
            "Fixed seed to use to hash property keys (0 means random)"
            "(with snapshots this option cannot override the baked-in seed)")
-DEFINE_maybe_bool(force_memory_constrained,
-           "force (if true) or prevent (if false) the runtime from treating "
-           "the device as being memory constrained.")
 
 // v8.cc
 DEFINE_bool(preemption, false,