Count closures using the feedback vector cell map, specialize if count==1.

src/compiler/pipeline.cc

Index: src/compiler/pipeline.cc
diff --git a/src/compiler/pipeline.cc b/src/compiler/pipeline.cc
index 8a11656b526f16053e6dbc645317d62e66bb7af1..bb4e3cfb8a6838f0f430fc842e3ba9e6525e71e7 100644
--- a/src/compiler/pipeline.cc
+++ b/src/compiler/pipeline.cc
@@ -594,6 +594,10 @@ PipelineCompilationJob::Status PipelineCompilationJob::PrepareJobImpl() {
     if (FLAG_inline_accessors) {
       info()->MarkAsAccessorInliningEnabled();
     }
+    if (info()->closure()->feedback_vector_cell()->map() ==
+        isolate()->heap()->one_closure_cell_map()) {
+      info()->MarkAsFunctionContextSpecializing();
+    }
   }
   if (!info()->is_optimizing_from_bytecode()) {
     if (!Compiler::EnsureDeoptimizationSupport(info())) return FAILED;