Fix a bunch of implicit casts detected by the Win64 compiler

samples/shell.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 187 matching lines @@
   FILE* file = fopen(name, "rb");
   if (file == NULL) return v8::Handle<v8::String>();
 
   fseek(file, 0, SEEK_END);
   int size = ftell(file);
   rewind(file);
 
   char* chars = new char[size + 1];
   chars[size] = '\0';
   for (int i = 0; i < size;) {
-    int read = fread(&chars[i], 1, size - i, file);
+    int read = static_cast<int>(fread(&chars[i], 1, size - i, file));
     i += read;
   }
   fclose(file);
   v8::Handle<v8::String> result = v8::String::New(chars, size);
   delete[] chars;
   return result;
 }
 
 
 // Process remaining command line arguments and execute files
@@ skipping 112 matching lines @@
       printf("^");
     }
     printf("\n");
     v8::String::Utf8Value stack_trace(try_catch->StackTrace());
     if (stack_trace.length() > 0) {
       const char* stack_trace_string = ToCString(stack_trace);
       printf("%s\n", stack_trace_string);
     }
   }
 }