Introduce a new growth criterion for the new space 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 25426d67acfa1e799521b08dfd7e676afa607da4..9645dda215d629cd691a46a469f241f15b7348bd 100644
--- a/src/flag-definitions.h
+++ b/src/flag-definitions.h
@@ -531,6 +531,9 @@ DEFINE_INT(max_semi_space_size, 0,
            "max size of a semi-space (in MBytes), the new space consists of two"
            "semi-spaces")
 DEFINE_INT(semi_space_growth_factor, 2, "factor by which to grow the new space")
+DEFINE_BOOL(experimental_new_space_growth_heuristic, false,
+            "Grow the new space based on the percentage of survivors instead "
+            "of their absolute value.")
 DEFINE_INT(max_old_space_size, 0, "max size of the old space (in Mbytes)")
 DEFINE_INT(max_executable_size, 0, "max size of executable memory (in Mbytes)")
 DEFINE_BOOL(gc_global, false, "always perform global GCs")