[future] Enable lazy feedback allocation in 'future' configuration

Bug: v8:8394
Change-Id: I5b4c02f5f36710b3fa15037e1fa1520b759447c4
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1611798
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Commit-Queue: Mythri Alle <mythria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61501}

src/flag-definitions.h

@@ -389,6 +389,7 @@ DEFINE_INT(budget_for_feedback_vector_allocation, 1 * KB,
            "The budget in amount of bytecode executed by a function before we "
            "decide to allocate feedback vectors")
 DEFINE_BOOL(lazy_feedback_allocation, false, "Allocate feedback vectors lazily")
+DEFINE_IMPLICATION(future, lazy_feedback_allocation)
 
 // Flags for Ignition.
 DEFINE_BOOL(ignition_elide_noneffectful_bytecodes, true,

test/mjsunit/regress/regress-crbug-961709-2.js

@@ -10,6 +10,7 @@ function foo() {
   return a[0];
 }
 
+%EnsureFeedbackVectorForFunction(foo);
 Object.setPrototypeOf(Array.prototype, new Int8Array());
 assertEquals(undefined, foo());
 assertEquals(undefined, foo());