[scanner] Extend fast-smi parsing to the entire range minus Smi::kMinValue

BUG=

Review URL: https://codereview.chromium.org/998893002

Cr-Commit-Position: refs/heads/master@{#27129}

src/scanner.cc

@@ -1000,7 +1000,7 @@ Token::Value Scanner::ScanNumber(bool seen_period) {
     // Parse decimal digits and allow trailing fractional part.
     if (kind == DECIMAL) {
       if (at_start) {
-        int value = 0;
+        uint64_t value = 0;
         while (IsDecimalDigit(c0_)) {
           value = 10 * value + (c0_ - '0');
 
@@ -1009,9 +1009,9 @@ Token::Value Scanner::ScanNumber(bool seen_period) {
           AddLiteralChar(first_char);
         }
 
-        if (next_.literal_chars->one_byte_literal().length() < 10 &&
-            c0_ != '.' && c0_ != 'e' && c0_ != 'E') {
-          smi_value_ = value;
+        if (next_.literal_chars->one_byte_literal().length() <= 10 &&
+            value <= Smi::kMaxValue && c0_ != '.' && c0_ != 'e' && c0_ != 'E') {
+          smi_value_ = static_cast<int>(value);
           literal.Complete();
           HandleLeadSurrogate();
 
@@ -1428,11 +1428,6 @@ double Scanner::DoubleValue() {
 }
 
 
-int Scanner::FindNumber(DuplicateFinder* finder, int value) {
-  return finder->AddNumber(literal_one_byte_string(), value);
-}
-
-
 int Scanner::FindSymbol(DuplicateFinder* finder, int value) {
   if (is_literal_one_byte()) {
     return finder->AddOneByteSymbol(literal_one_byte_string(), value);

src/scanner.h

@@ -427,7 +427,6 @@ class Scanner {
     }
   }
 
-  int FindNumber(DuplicateFinder* finder, int value);
   int FindSymbol(DuplicateFinder* finder, int value);
 
   UnicodeCache* unicode_cache() { return unicode_cache_; }