[scanner] Use AdvanceUntil in SkipWhiteSpace

Change-Id: I4a578589290e91da2eae4cef8f936e6c888e177c
Reviewed-on: https://chromium-review.googlesource.com/1194015Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55497}

src/parsing/scanner-inl.h

@@ -150,24 +150,23 @@ static const Token::Value one_char_tokens[] = {
 // clang-format on
 
 V8_INLINE Token::Value Scanner::SkipWhiteSpace() {
-  int start_position = source_pos();
-
   // We won't skip behind the end of input.
   DCHECK(!unicode_cache_->IsWhiteSpaceOrLineTerminator(kEndOfInput));
 
+  // Make sure we skip at least one character.
+  if (!unicode_cache_->IsWhiteSpaceOrLineTerminator(c0_)) return Token::ILLEGAL;
+  if (!next().after_line_terminator && unibrow::IsLineTerminator(c0_)) {
+    next().after_line_terminator = true;
+  }
+
   // Advance as long as character is a WhiteSpace or LineTerminator.
-  while (unicode_cache_->IsWhiteSpaceOrLineTerminator(c0_)) {
-    if (!next().after_line_terminator && unibrow::IsLineTerminator(c0_)) {
+  AdvanceUntil([=](uc32 c0) {
+    if (!unicode_cache_->IsWhiteSpaceOrLineTerminator(c0)) return true;
+    if (!next().after_line_terminator && unibrow::IsLineTerminator(c0)) {
       next().after_line_terminator = true;
     }
-    Advance();
-  }
-
-  // Return whether or not we skipped any characters.
-  if (source_pos() == start_position) {
-    DCHECK_NE('0', c0_);
-    return Token::ILLEGAL;
-  }
+    return false;
+  });
 
   return Token::WHITESPACE;
 }

src/parsing/scanner.cc

@@ -284,7 +284,7 @@ Token::Value Scanner::SkipSingleLineComment() {
   // separately by the lexical grammar and becomes part of the
   // stream of input elements for the syntactic grammar (see
   // ECMA-262, section 7.4).
-  AdvanceUntil([](uc32 c0_) { return unibrow::IsLineTerminator(c0_); });
+  AdvanceUntil([](uc32 c0) { return unibrow::IsLineTerminator(c0); });
 
   return Token::WHITESPACE;
 }