Run Crankshaft on a separate thread.

src/d8.cc

Index: src/d8.cc
diff --git a/src/d8.cc b/src/d8.cc
index ddd4100fa8209cb9d6075c466229a05eaa869ecd..12c25da1b04ed9cda0081e8d79d866800ebaeaa5 100644
--- a/src/d8.cc
+++ b/src/d8.cc
@@ -1547,7 +1547,9 @@ int Shell::Main(int argc, char* argv[]) {
       result = RunMain(argc, argv);
     }
     printf("======== Full Deoptimization =======\n");
+    Isolate::GetCurrent()->Enter();
     Testing::DeoptimizeAll();
+    Isolate::GetCurrent()->Exit();
 #if !defined(V8_SHARED)
   } else if (i::FLAG_stress_runs > 0) {
     int stress_runs = i::FLAG_stress_runs;