[generators] Desugar yield*.

src/parsing/rewriter.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/parsing/rewriter.h"
 
 #include "src/ast/ast.h"
 #include "src/ast/scopes.h"
 #include "src/parsing/parser.h"
 
@@ skipping 207 matching lines @@
 void Processor::VisitTryFinallyStatement(TryFinallyStatement* node) {
   // Rewrite both try and finally block (in reverse order).
   bool set_after = is_set_;
   is_set_ = true;  // Don't normally need to assign in finally block.
   Visit(node->finally_block());
   node->set_finally_block(replacement_->AsBlock());
   {  // Save .result value at the beginning of the finally block and restore it
      // at the end again: ".backup = .result; ...; .result = .backup"
      // This is necessary because the finally block does not normally contribute
      // to the completion value.
+    CHECK(scope() != nullptr);
     Variable* backup = scope()->NewTemporary(
         factory()->ast_value_factory()->dot_result_string());
     Expression* backup_proxy = factory()->NewVariableProxy(backup);
     Expression* result_proxy = factory()->NewVariableProxy(result_);
     Expression* save = factory()->NewAssignment(
         Token::ASSIGN, backup_proxy, result_proxy, RelocInfo::kNoPosition);
     Expression* restore = factory()->NewAssignment(
         Token::ASSIGN, result_proxy, backup_proxy, RelocInfo::kNoPosition);
     node->finally_block()->statements()->InsertAt(
         0, factory()->NewExpressionStatement(save, RelocInfo::kNoPosition),
@@ skipping 156 matching lines @@
           processor.SetResult(undef), expr->position());
       body->Add(completion, factory->zone());
     }
   }
   return true;
 }
 
 
 }  // namespace internal
 }  // namespace v8