Fix arrow functions requiring context without slots.

src/compiler/ast-graph-builder.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/ast-graph-builder.h"
 
 #include "src/compiler.h"
 #include "src/compiler/ast-loop-assignment-analyzer.h"
 #include "src/compiler/control-builders.h"
 #include "src/compiler/js-type-feedback.h"
@@ skipping 507 matching lines @@
   Node* patched_receiver = nullptr;
   if (scope->has_this_declaration()) {
     Node* original_receiver = NewNode(common()->Parameter(0), graph()->start());
     patched_receiver = BuildPatchReceiverToGlobalProxy(original_receiver);
     if (scope->receiver()->IsStackAllocated()) {
       env.Bind(scope->receiver(), patched_receiver);
     }
   }
 
   // Build function context only if there are context allocated variables.
-  int heap_slots = info()->num_heap_slots() - Context::MIN_CONTEXT_SLOTS;
-  if (heap_slots > 0) {
+  if (info()->num_heap_slots() > 0) {
     // Push a new inner context scope for the function.
     Node* inner_context =
         BuildLocalFunctionContext(function_context_.get(), patched_receiver);
     ContextScope top_context(this, scope, inner_context);
     CreateGraphBody(stack_check);
   } else {
     // Simply use the outer function context in building the graph.
     CreateGraphBody(stack_check);
   }
 
@@ skipping 3239 matching lines @@
     // Phi does not exist yet, introduce one.
     value = NewPhi(inputs, value, control);
     value->ReplaceInput(inputs - 1, other);
   }
   return value;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8