Follow-up fix to my change to IsPowerOfTwo: Alignment of one means no alignment, not zero.

runtime/vm/native_arguments.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_NATIVE_ARGUMENTS_H_
 #define VM_NATIVE_ARGUMENTS_H_
 
 #include "platform/assert.h"
 #include "vm/globals.h"
 #include "vm/handles_impl.h"
@@ skipping 11 matching lines @@
 class Isolate;
 class Object;
 class RawObject;
 class Simulator;
 
 #if defined(TESTING) || defined(DEBUG)
 
 #if defined(USING_SIMULATOR)
 #define CHECK_STACK_ALIGNMENT {                                                \
   uword current_sp = Simulator::Current()->get_register(SPREG);                \
-  ASSERT((OS::ActivationFrameAlignment() == 0) ||                              \
-         (Utils::IsAligned(current_sp, OS::ActivationFrameAlignment())));      \
+  ASSERT(Utils::IsAligned(current_sp, OS::ActivationFrameAlignment()));        \
 }
 #elif defined(TARGET_OS_WINDOWS)
 // The compiler may dynamically align the stack on Windows, so do not check.
 #define CHECK_STACK_ALIGNMENT { }
 #else
 #define CHECK_STACK_ALIGNMENT {                                                \
   uword (*func)() =                                                            \
       reinterpret_cast<uword (*)()>(StubCode::GetStackPointerEntryPoint());    \
   uword current_sp = func();                                                   \
-  ASSERT((OS::ActivationFrameAlignment() == 0) ||                              \
-         (Utils::IsAligned(current_sp, OS::ActivationFrameAlignment())));      \
+  ASSERT(Utils::IsAligned(current_sp, OS::ActivationFrameAlignment()));        \
 }
 #endif
 
 #define VERIFY_ON_TRANSITION                                                   \
   if (FLAG_verify_on_transition) {                                             \
     VerifyPointersVisitor::VerifyPointers();                                   \
     Isolate::Current()->heap()->Verify();                                      \
   }
 #define TRACE_NATIVES(name)                                                    \
   if (FLAG_trace_natives) {                                                    \
@@ skipping 138 matching lines @@
 
   Isolate* isolate_;  // Current isolate pointer.
   int argc_tag_;  // Encodes argument count and invoked native call type.
   RawObject*(*argv_)[];  // Pointer to an array of arguments to runtime call.
   RawObject** retval_;  // Pointer to the return value area.
 };
 
 }  // namespace dart
 
 #endif  // VM_NATIVE_ARGUMENTS_H_