Scanner / Unicode decoding: use size_t instead of unsigned.

test/cctest/test-parsing.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 678 matching lines @@
     CHECK_EQU(i + 1, stream.pos());
   }
   for (int i = kMaxUC16Char; i >= 0; i--) {
     CHECK_EQU(i + 1, stream.pos());
     stream.PushBack(i);
     CHECK_EQU(i, stream.pos());
   }
   int i = 0;
   while (stream.pos() < kMaxUC16CharU) {
     CHECK_EQU(i, stream.pos());
-    unsigned progress = stream.SeekForward(12);
+    int progress = static_cast<int>(stream.SeekForward(12));
     i += progress;
     int32_t c = stream.Advance();
     if (i <= kMaxUC16Char) {
       CHECK_EQ(i, c);
     } else {
       CHECK_EQ(-1, c);
     }
     i += 1;
     CHECK_EQU(i, stream.pos());
   }
@@ skipping 4267 matching lines @@
     "const x = 1;",
     "class C {}",
     NULL};
 
   static const ParserFlag always_flags[] = {
     kAllowHarmonyClasses, kAllowHarmonyScoping
   };
   RunParserSyncTest(context_data, statement_data, kError, NULL, 0,
                     always_flags, arraysize(always_flags));
 }