Make --future imply --concurrent-inlining.

This gives us better test coverage.

Also enable --strict-heap-broker by default. I think this
flag is no longer necessary and can be removed soon.

Bug: v8:7790
Change-Id: I55d43dea45ff99bb753189b0d019f945b61752ac
Reviewed-on: https://chromium-review.googlesource.com/c/1298898
Commit-Queue: Georg Neis <neis@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56991}

src/flag-definitions.h

@@ -381,7 +381,8 @@ DEFINE_BOOL(block_concurrent_recompilation, false,
             "block queued jobs until released")
 DEFINE_BOOL(concurrent_inlining, false,
             "run optimizing compiler's inlining phase on a separate thread")
-DEFINE_BOOL(strict_heap_broker, false, "fail on incomplete serialization")
+DEFINE_IMPLICATION(future, concurrent_inlining)
+DEFINE_BOOL(strict_heap_broker, true, "fail on incomplete serialization")
 DEFINE_BOOL(trace_heap_broker, false, "trace the heap broker")
 
 // Flags for stress-testing the compiler.