Remove unused code for IsFutureStrictReserved.

src/parsing/parser.cc

Index: src/parsing/parser.cc
diff --git a/src/parsing/parser.cc b/src/parsing/parser.cc
index 0c69c92d1ef1ccf8bbb4ef3c06c2d66735566d7a..284988fa00d961c864c1d7caf17c99803087dae5 100644
--- a/src/parsing/parser.cc
+++ b/src/parsing/parser.cc
@@ -1645,6 +1645,7 @@ Statement* Parser::DeclareNative(const AstRawString* name, int pos, bool* ok) {
 
 ZoneList<const AstRawString*>* Parser::DeclareLabel(
     ZoneList<const AstRawString*>* labels, VariableProxy* var, bool* ok) {
+  DCHECK(IsIdentifier(var));
   const AstRawString* label = var->raw_name();
   // TODO(1240780): We don't check for redeclaration of labels
   // during preparsing since keeping track of the set of active