[modules] Infer strict mode from within scope object

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 "src/accessors.h"
 #include "src/ast/scopeinfo.h"
 #include "src/bootstrapper.h"
 #include "src/messages.h"
@@ skipping 157 matching lines @@
   function_ = nullptr;
   arguments_ = nullptr;
   this_function_ = nullptr;
   scope_inside_with_ = false;
   scope_calls_eval_ = false;
   scope_uses_arguments_ = false;
   scope_uses_super_property_ = false;
   asm_module_ = false;
   asm_function_ = outer_scope != NULL && outer_scope->asm_module_;
   // Inherit the language mode from the parent scope.
-  language_mode_ = outer_scope != NULL ? outer_scope->language_mode_ : SLOPPY;
+  language_mode_ =
+      is_module_scope()
+          ? STRICT
+          : (outer_scope != NULL ? outer_scope->language_mode_ : SLOPPY);
   outer_scope_calls_sloppy_eval_ = false;
   inner_scope_calls_eval_ = false;
   scope_nonlinear_ = false;
   force_eager_compilation_ = false;
   force_context_allocation_ = (outer_scope != NULL && !is_function_scope())
       ? outer_scope->has_forced_context_allocation() : false;
   num_var_or_const_ = 0;
   num_stack_slots_ = 0;
   num_heap_slots_ = 0;
   num_global_slots_ = 0;
@@ skipping 1310 matching lines @@
       function_ != NULL && function_->proxy()->var()->IsContextSlot();
   return num_heap_slots() - Context::MIN_CONTEXT_SLOTS - num_global_slots() -
          (is_function_var_in_context ? 1 : 0);
 }
 
 
 int Scope::ContextGlobalCount() const { return num_global_slots(); }
 
 }  // namespace internal
 }  // namespace v8