Remove CONST_LEGACY VariableMode

src/full-codegen/x64/full-codegen-x64.cc

Index: src/full-codegen/x64/full-codegen-x64.cc
diff --git a/src/full-codegen/x64/full-codegen-x64.cc b/src/full-codegen/x64/full-codegen-x64.cc
index 5f91afaf49f737eef29340c7f282c9230a844d7b..d6927c3e8409b5d022d3943fde5cf5c5ade26aac 100644
--- a/src/full-codegen/x64/full-codegen-x64.cc
+++ b/src/full-codegen/x64/full-codegen-x64.cc
@@ -2064,10 +2064,10 @@ void FullCodeGenerator::EmitVariableAssignment(Variable* var, Token::Value op,
       __ CallRuntime(Runtime::kThrowReferenceError);
       __ bind(&assign);
     }
-    if (var->mode() == CONST) {
-      __ CallRuntime(Runtime::kThrowConstAssignError);
-    } else {
+    if (var->mode() != CONST) {
       EmitStoreToStackLocalOrContextSlot(var, location);
+    } else if (var->throw_on_const_assignment(language_mode())) {
+      __ CallRuntime(Runtime::kThrowConstAssignError);
     }
 
   } else if (var->is_this() && var->mode() == CONST && op == Token::INIT) {
@@ -2083,7 +2083,8 @@ void FullCodeGenerator::EmitVariableAssignment(Variable* var, Token::Value op,
     __ bind(&uninitialized_this);
     EmitStoreToStackLocalOrContextSlot(var, location);
 
-  } else if (!var->is_const_mode() || op == Token::INIT) {
+  } else {
+    DCHECK(var->mode() != CONST || op == Token::INIT);
     if (var->IsLookupSlot()) {
       // Assignment to var.
       __ Push(var->name());
@@ -2104,13 +2105,6 @@ void FullCodeGenerator::EmitVariableAssignment(Variable* var, Token::Value op,
       }
       EmitStoreToStackLocalOrContextSlot(var, location);
     }
-
-  } else {
-    DCHECK(var->mode() == CONST_LEGACY && op != Token::INIT);
-    if (is_strict(language_mode())) {
-      __ CallRuntime(Runtime::kThrowConstAssignError);
-    }
-    // Silently ignore store in sloppy mode.
   }
 }