Fix Windows build by removing an overly strict assertion.

runtime/vm/object.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_OBJECT_H_
 #define VM_OBJECT_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/utils.h"
@@ skipping 3610 matching lines @@
   }
 
   // We would have a VisitPointers function here to traverse all the
   // embedded objects in the instructions using pointer_offsets.
 
   static const intptr_t kBytesPerElement =
       sizeof(reinterpret_cast<RawCode*>(0)->data_[0]);
   static const intptr_t kMaxElements = kSmiMax / kBytesPerElement;
 
   static intptr_t InstanceSize() {
-    ASSERT(sizeof(RawCode) == OFFSET_OF(RawCode, data_));

[Ivan Posva, 2014/06/04 15:53:14]

There are too many things riding on the assertion that sizeof(RawCode) gives us
the correct information. We will have to solve this differently.

[Florian Schneider, 2014/06/06 09:13:03]

Yes, this is fragile: InstanceSize(intptr_t len) needs to be correct. This means
that RoundedAllocationSize must match what the C++ compiler produces. There are
differences betwwen MSVC and g++: sizeof(RawCode) is 72 on my Linux machine, and
80 on Win32.

OFFSET_OF(data_) is 72 on Linux, and 76 on Win32.

In this instance the RoundedAllocationSize would be still 80 since we round up
to multiples of 8 (kObjectAlignment), but there is no guarantee that these
things match.

     return 0;
   }
   static intptr_t InstanceSize(intptr_t len) {
     ASSERT(0 <= len && len <= kMaxElements);
     return RoundedAllocationSize(sizeof(RawCode) + (len * kBytesPerElement));
   }
   static RawCode* FinalizeCode(const Function& function,
                                Assembler* assembler,
                                bool optimized = false);
   static RawCode* FinalizeCode(const char* name,
@@ skipping 3464 matching lines @@
 
 
 RawObject* MegamorphicCache::GetTargetFunction(const Array& array,
                                                intptr_t index) {
   return array.At((index * kEntryLength) + kTargetFunctionIndex);
 }
 
 }  // namespace dart
 
 #endif  // VM_OBJECT_H_