Fixed Window's Debug warning, results in compilation failure.

runtime/vm/heap.h

 // 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.
 
 #ifndef VM_HEAP_H_
 #define VM_HEAP_H_
 
 #include "platform/assert.h"
 #include "vm/allocation.h"
 #include "vm/flags.h"
@@ skipping 43 matching lines @@
     kPromotion,
     kOldSpace,
     kFull,
     kGCAtAlloc,
     kGCTestCase,
   };
 
 #if defined(DEBUG)
   // Pattern for unused new space and swept old space.
   static const uint64_t kZap64Bits = 0xf3f3f3f3f3f3f3f3;
-  static const uint32_t kZap32Bits = static_cast<uint32_t>(kZap64Bits);
-  static const uint8_t kZapByte = static_cast<uint8_t>(kZap64Bits);
+  static const uint32_t kZap32Bits = 0xf3f3f3f3;
+  static const uint8_t kZapByte = 0xf3;
 #endif  // DEBUG
 
   ~Heap();
 
   Scavenger* new_space() const { return new_space_; }
   PageSpace* old_space() const { return old_space_; }
 
   uword Allocate(intptr_t size, Space space) {
     ASSERT(!read_only_);
     switch (space) {
@@ skipping 282 matching lines @@
   NoHeapGrowthControlScope();
   ~NoHeapGrowthControlScope();
  private:
   bool current_growth_controller_state_;
   DISALLOW_COPY_AND_ASSIGN(NoHeapGrowthControlScope);
 };
 
 }  // namespace dart
 
 #endif  // VM_HEAP_H_