[turbofan] Enable Promise constructor inlining by default

Bug: v8:7584
Change-Id: I7443c28c74676ee1f27550674c8f712594e21cc7
Reviewed-on: https://chromium-review.googlesource.com/992314Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52341}

src/flag-definitions.h

@@ -488,7 +488,7 @@ DEFINE_BOOL(turbo_store_elimination, true,
 DEFINE_BOOL(trace_store_elimination, false, "trace store elimination")
 DEFINE_BOOL(turbo_rewrite_far_jumps, true,
             "rewrite far to near jumps (ia32,x64)")
-DEFINE_BOOL(experimental_inline_promise_constructor, false,
+DEFINE_BOOL(experimental_inline_promise_constructor, true,
             "inline the Promise constructor in TurboFan")
 
 #ifdef DISABLE_UNTRUSTED_CODE_MITIGATIONS