Remove more dead code now that legacy const is gone

src/compiler/ast-graph-builder.cc

 // Copyright 2014 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/compiler/ast-graph-builder.h"
 
 #include "src/ast/scopes.h"
 #include "src/compiler.h"
 #include "src/compiler/ast-loop-assignment-analyzer.h"
 #include "src/compiler/control-builders.h"
@@ skipping 1114 matching lines @@
       }
       break;
     case VariableLocation::CONTEXT:
       if (hole_init) {
         Node* value = jsgraph()->TheHoleConstant();
         const Operator* op = javascript()->StoreContext(0, variable->index());
         NewNode(op, current_context(), value);
       }
       break;
     case VariableLocation::LOOKUP: {
+      DCHECK(!hole_init);
       Node* name = jsgraph()->Constant(variable->name());
-      // For variables we must not push an initial value (such as 'undefined')
-      // because we may have a (legal) redeclaration and we must not destroy
-      // the current value.
-      Node* value =
-          hole_init ? jsgraph()->TheHoleConstant()
-                    : jsgraph()->ZeroConstant();  // Indicates no initial value.
+      Node* value = jsgraph()->ZeroConstant();  // Indicates no initial value.
       Node* attr =
           jsgraph()->Constant(variable->DeclarationPropertyAttributes());
       const Operator* op =
           javascript()->CallRuntime(Runtime::kDeclareLookupSlot);
       Node* store = NewNode(op, name, value, attr);
       PrepareFrameState(store, decl->proxy()->id());
       break;
     }
   }
 }
@@ skipping 3217 matching lines @@
     // Phi does not exist yet, introduce one.
     value = NewPhi(inputs, value, control);
     value->ReplaceInput(inputs - 1, other);
   }
   return value;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8