VM: Fix bug in stack map builder.

runtime/vm/locations.h

 // Copyright (c) 2013, 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.
 
 #ifndef VM_LOCATIONS_H_
 #define VM_LOCATIONS_H_
 
 #include "vm/allocation.h"
 #include "vm/assembler.h"
 #include "vm/bitfield.h"
@@ skipping 441 matching lines @@
   SmallSet() : data_(0) { }
 
   explicit SmallSet(intptr_t data) : data_(data) { }
 
   bool Contains(T value) const { return (data_ & ToMask(value)) != 0; }
 
   void Add(T value) { data_ |= ToMask(value); }
 
   void Remove(T value) { data_ &= ~ToMask(value); }
 
-  bool IsEmpty() const { return data_ != 0; }
+  bool IsEmpty() const { return data_ == 0; }
 
   intptr_t data() const { return data_; }
 
  private:
   static intptr_t ToMask(T value) {
     ASSERT(static_cast<intptr_t>(value) < (kWordSize * kBitsPerByte));
     return 1 << static_cast<intptr_t>(value);
   }
 
   intptr_t data_;
@@ skipping 236 matching lines @@
 
 #if defined(DEBUG)
   intptr_t writable_inputs_;
 #endif
 };
 
 
 }  // namespace dart
 
 #endif  // VM_LOCATIONS_H_