Remove unused code for IsFutureStrictReserved.

src/parsing/preparser.h

Index: src/parsing/preparser.h
diff --git a/src/parsing/preparser.h b/src/parsing/preparser.h
index f8afe17b0a0b8af8a0e848e7893495259ece0b25..a1e1f05c58906b02d9e7090027fa441f3a1827ea 100644
--- a/src/parsing/preparser.h
+++ b/src/parsing/preparser.h
@@ -79,11 +79,6 @@ class PreParserIdentifier {
   bool IsConstructor() const { return type_ == kConstructorIdentifier; }
   bool IsEnum() const { return type_ == kEnumIdentifier; }
   bool IsAwait() const { return type_ == kAwaitIdentifier; }
-  bool IsFutureStrictReserved() const {
-    return type_ == kFutureStrictReservedIdentifier ||
-           type_ == kLetIdentifier || type_ == kStaticIdentifier ||
-           type_ == kYieldIdentifier;
-  }
 
   // Allow identifier->name()[->length()] to work. The preparser
   // does not need the actual positions/lengths of the identifiers.
@@ -1009,8 +1004,7 @@ class PreParser : public ParserBase<PreParser> {
       bool* ok) {
     DCHECK(!expr.AsIdentifier().IsEnum());
     DCHECK(!parsing_module_ || !expr.AsIdentifier().IsAwait());
-    DCHECK(is_sloppy(language_mode()) ||
-           !IsFutureStrictReserved(expr.AsIdentifier()));
+    DCHECK(IsIdentifier(expr));
     return labels;
   }
 
@@ -1125,10 +1119,6 @@ class PreParser : public ParserBase<PreParser> {
     return identifier.IsAwait();
   }
 
-  V8_INLINE bool IsFutureStrictReserved(PreParserIdentifier identifier) const {
-    return identifier.IsFutureStrictReserved();
-  }
-
   // Returns true if the expression is of type "this.foo".
   V8_INLINE static bool IsThisProperty(PreParserExpression expression) {
     return expression.IsThisProperty();