[interpreter] Strengthen a DCHECK.

src/interpreter/bytecode-generator.cc

 // Copyright 2015 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/interpreter/bytecode-generator.h"
 
 #include "src/ast/scopes.h"
 #include "src/code-stubs.h"
 #include "src/compilation-info.h"
 #include "src/compiler.h"
@@ skipping 929 matching lines @@
           .CallRuntime(Runtime::kDeclareEvalVar, name, 1);
       break;
     }
     case VariableLocation::MODULE:
       UNREACHABLE();
   }
 }
 
 void BytecodeGenerator::VisitFunctionDeclaration(FunctionDeclaration* decl) {
   Variable* variable = decl->proxy()->var();
+  DCHECK(variable->mode() == LET || variable->mode() == VAR);
   switch (variable->location()) {
     case VariableLocation::GLOBAL:
     case VariableLocation::UNALLOCATED: {
       FeedbackVectorSlot slot = decl->proxy()->VariableFeedbackSlot();
       globals_builder()->AddFunctionDeclaration(slot, decl->fun());
       break;
     }
     case VariableLocation::PARAMETER:
     case VariableLocation::LOCAL: {
       VisitForAccumulatorValue(decl->fun());
-      DCHECK(variable->mode() == LET || variable->mode() == VAR ||
-             variable->mode() == CONST);
       VisitVariableAssignment(variable, Token::INIT,
                               FeedbackVectorSlot::Invalid());
       break;
     }
     case VariableLocation::CONTEXT: {
       DCHECK_EQ(0, execution_context()->ContextChainDepth(variable->scope()));
       VisitForAccumulatorValue(decl->fun());
       builder()->StoreContextSlot(execution_context()->reg(),
                                   variable->index());
       break;
@@ skipping 2418 matching lines @@
   return execution_context()->scope()->language_mode();
 }
 
 int BytecodeGenerator::feedback_index(FeedbackVectorSlot slot) const {
   return TypeFeedbackVector::GetIndex(slot);
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8