url: fast path ascii domains, do not run ToASCII

To match browser behavior fast path ascii only domains and
do not run ToASCII on them.

Fixes: nodejs#12965
Refs: nodejs#12966
Refs: whatwg/url#309

src/node_url.cc

@@ -130,6 +130,9 @@ enum url_error_cb_args {
  return str.length() >= 2 && name(str[0], str[1]); \
  }
 
+// https://infra.spec.whatwg.org/#ascii-code-point
+CHAR_TEST(8, IsASCIICodePoint, (ch >= '\0' && ch <= '\x7f'))
+
 // https://infra.spec.whatwg.org/#ascii-tab-or-newline
 CHAR_TEST(8, IsASCIITabOrNewline, (ch == '\t' || ch == '\n' || ch == '\r'))
 
@@ -829,10 +832,10 @@ static url_host_type ParseOpaqueHost(url_host* host,
  return type;
 }
 
-static inline bool IsAllASCII(std::string* input) {
- for (size_t n = 0; n < input->size(); n++) {
- const char ch = (*input)[n];
- if (ch & 0x80) {
+static inline bool IsAllASCII(const std::string& input) {
+ for (size_t n = 0; n < input.size(); n++) {
+ const char ch = input[n];
+ if (!IsASCIICodePoint(ch)) {
  return false;
  }
  }
@@ -865,13 +868,13 @@ static url_host_type ParseHost(url_host* host,
 
  // Match browser behavior for ASCII only domains
  // and do not run them through ToASCII algorithm.
- if (IsAllASCII(&decoded)) {
- // Lowercase aschii domains
+ if (IsAllASCII(decoded)) {
+ // Lowercase ASCII domains
  for (size_t n = 0; n < decoded.size(); n++) {
- decoded[n] = std::tolower(decoded[n]);
+ decoded[n] = ASCIILowercase(decoded[n]);
  }
  } else {
- // Then we have to punycode toASCII
+ // Then we have to Unicode IDNA toASCII
  if (!ToASCII(&decoded, &decoded))
  goto end;
  }