Move pre-declaring the this variable to Scope::Analyze

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/bootstrapper.h"
@@ skipping 393 matching lines @@
   DeclarationScope* scope = info->literal()->scope();
 
   // We are compiling one of three cases:
   // 1) top-level code,
   // 2) a function/eval/module on the top-level
   // 3) a function/eval in a scope that was already resolved.
   DCHECK(scope->scope_type() == SCRIPT_SCOPE ||
          scope->outer_scope()->scope_type() == SCRIPT_SCOPE ||
          scope->outer_scope()->already_resolved_);
 
+  // If there's a chance that there's a reference to global 'this', predeclare
+  // it as a dynamic global on the script scope.
+  if (scope->GetReceiverScope()->is_script_scope()) {
+    info->script_scope()->DeclareDynamicGlobal(
+        info->ast_value_factory()->this_string(), Variable::THIS);
+  }
+
   scope->AllocateVariables(info, mode);
 
 #ifdef DEBUG
   if (info->script_is_native() ? FLAG_print_builtin_scopes
                                : FLAG_print_scopes) {
     scope->Print();
   }
   scope->CheckScopePositions();
   scope->CheckZones();
 #endif
@@ skipping 1229 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