Fix for bug 1229: Unary operator plus is not allowed ... except for literals.

runtime/vm/scanner.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/scanner.h"
 
 #include "platform/assert.h"
 #include "vm/flags.h"
 #include "vm/object.h"
 #include "vm/thread.h"
@@ skipping 100 matching lines @@
 bool Scanner::IsLetter(int32_t c) {
   return (('A' <= c) && (c <= 'Z')) || (('a' <= c) && (c <= 'z'));
 }
 
 
 bool Scanner::IsDecimalDigit(int32_t c) {
   return '0' <= c && c <= '9';
 }
 
 
+bool Scanner::IsNumberStart(int32_t ch) {
+  return IsDecimalDigit(ch) || ch == '.';
+}
+
+
 bool Scanner::IsHexDigit(int32_t c) {
   return IsDecimalDigit(c)
          || (('A' <= c) && (c <= 'F'))
          || (('a' <= c) && (c <= 'f'));
 }
 
 
 bool Scanner::IsIdentStartChar(int32_t c) {
   return IsLetter(c) || (c == '_') || (c == '$');
 }
@@ skipping 455 matching lines @@
         ScanLiteralStringChars(false);
       }
       break;
     }
     switch (c0_) {
       case '\0':
         current_token_.kind = Token::kEOS;
         break;
 
       case '+':  // +  ++  +=
-        Recognize(Token::kADD);
+        ReadChar();
+        current_token_.kind =
+            IsNumberStart(c0_) ? Token::kTIGHTADD : Token::kADD;
         if (c0_ == '+') {
           Recognize(Token::kINCR);
         } else if (c0_ == '=') {
           Recognize(Token::kASSIGN_ADD);
         }
         break;
 
       case '-':  // -  --  -=
         Recognize(Token::kSUB);
         if (c0_ == '-') {
@@ skipping 276 matching lines @@
               "%c%"PRIxPTR, kPrivateKeySeparator, key_value);
   const String& result = String::Handle(String::New(private_key));
   return result.raw();
 }
 
 
 void Scanner::InitOnce() {
 }
 
 }  // namespace dart