[ignition] Fix hole check for dynamic local variables

src/ast/scopes.cc

 // Copyright 2012 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/ast/scopes.h"
 
 #include <set>
 
 #include "src/accessors.h"
 #include "src/ast/ast.h"
@@ skipping 1632 matching lines @@
 void Scope::ResolveVariable(ParseInfo* info, VariableProxy* proxy) {
   DCHECK(info->script_scope()->is_script_scope());
   DCHECK(!proxy->is_resolved());
   Variable* var = LookupRecursive(proxy, nullptr);
   ResolveTo(info, proxy, var);
 }
 
 namespace {
 
 bool AccessNeedsHoleCheck(Variable* var, VariableProxy* proxy, Scope* scope) {
+  if (var->mode() == DYNAMIC_LOCAL) {
+    return AccessNeedsHoleCheck(var->local_if_not_shadowed(), proxy, scope);

[adamk, 2016/12/07 17:37:41]

Can you add a DCHECK here:

DCHECK(!var->binding_needs_init());

And a comment? The comment should say that dynamically-introduced variables
themselves never need a hole check (since they're VAR bindings, either from var
or function declarations), but that the thing they shadow might need a hole
check.

+  }
+
   if (!var->binding_needs_init()) {
     return false;
   }
 
   // It's impossible to eliminate module import hole checks here, because it's
   // unknown at compilation time whether the binding referred to in the
   // exporting module itself requires hole checks.
   if (var->location() == VariableLocation::MODULE && !var->IsExport()) {
     return true;
   }
@@ skipping 401 matching lines @@
   Variable* function =
       is_function_scope() ? AsDeclarationScope()->function_var() : nullptr;
   bool is_function_var_in_context =
       function != nullptr && function->IsContextSlot();
   return num_heap_slots() - Context::MIN_CONTEXT_SLOTS -
          (is_function_var_in_context ? 1 : 0);
 }
 
 }  // namespace internal
 }  // namespace v8