Enable FLAG_feedback_allocation_on_bytecode_size

This flag enables feedback allocation heuristics to be based on the
function size. The threshold for feedback allocation is set to
4 * bytecode size to roughly mimic the allocation after 4 invocations.

Change-Id: Ia840cd526e3718d4267e01c688c6c6467e352d72
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2685175Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Commit-Queue: Mythri Alle <mythria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#72631}

src/flags/flag-definitions.h

@@ -505,7 +505,7 @@ DEFINE_INT(budget_for_feedback_vector_allocation, 1 * KB,
            "decide to allocate feedback vectors")
 DEFINE_INT(scale_factor_for_feedback_allocation, 4,
            "scale bytecode size for feedback vector allocation.")
-DEFINE_BOOL(feedback_allocation_on_bytecode_size, false,
+DEFINE_BOOL(feedback_allocation_on_bytecode_size, true,
             "Instead of a fixed budget for lazy feedback vector allocation, "
             "scale it based in the bytecode size.")
 DEFINE_BOOL(lazy_feedback_allocation, true, "Allocate feedback vectors lazily")