[ast] Mark temporaries as maybe-assigned by default.

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 690 matching lines @@
     variables_.Add(zone(), function_);
   }
   return function_;
 }
 
 Variable* DeclarationScope::DeclareGeneratorObjectVar(
     const AstRawString* name) {
   DCHECK(is_function_scope() || is_module_scope());
   DCHECK_NULL(generator_object_var());
 
-  Variable* result = EnsureRareData()->generator_object = NewTemporary(name);
+  Variable* result = EnsureRareData()->generator_object =
+      NewTemporary(name, kNotAssigned);
   result->set_is_used();
   return result;
 }
 
 Variable* DeclarationScope::DeclarePromiseVar(const AstRawString* name) {
   DCHECK(is_function_scope());
   DCHECK_NULL(promise_var());
   Variable* result = EnsureRareData()->promise = NewTemporary(name);
   result->set_is_used();
   return result;
@@ skipping 475 matching lines @@
     if (var == next) {
       current->set_next_unresolved(next->next_unresolved());
       var->set_next_unresolved(nullptr);
       return true;
     }
     current = next;
   }
   return false;
 }
 
-Variable* Scope::NewTemporary(const AstRawString* name) {
+Variable* Scope::NewTemporary(const AstRawString* name,
+                              MaybeAssignedFlag maybe_assigned) {
   DeclarationScope* scope = GetClosureScope();
   Variable* var = new (zone())
       Variable(scope, name, TEMPORARY, NORMAL_VARIABLE, kCreatedInitialized);
   scope->AddLocal(var);
+  if (maybe_assigned == kMaybeAssigned) var->set_maybe_assigned();
   return var;
 }
 
 Declaration* Scope::CheckConflictingVarDeclarations() {
   for (Declaration* decl : decls_) {
     VariableMode mode = decl->proxy()->var()->mode();
     if (IsLexicalVariableMode(mode) && !is_block_scope()) continue;
 
     // Iterate through all scopes until and including the declaration scope.
     Scope* previous = NULL;
@@ skipping 1060 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