Fix vm code base so that it can be built for --arch=simarm (no snapshot yet).

runtime/vm/assembler_macros_arm.cc

Index: runtime/vm/assembler_macros_arm.cc
===================================================================
--- runtime/vm/assembler_macros_arm.cc	(revision 0)
+++ runtime/vm/assembler_macros_arm.cc	(revision 0)
@@ -0,0 +1,34 @@
+// 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.
+
+#include "vm/globals.h"
+#if defined(TARGET_ARCH_ARM)
+
+#include "vm/assembler_macros.h"
+
+namespace dart {
+
+void AssemblerMacros::TryAllocate(Assembler* assembler,
+                                  const Class& cls,
+                                  Label* failure,
+                                  bool near_jump,
+                                  Register instance_reg) {
+  UNIMPLEMENTED();
+}
+
+
+void AssemblerMacros::EnterDartFrame(Assembler* assembler,
+                                     intptr_t frame_size) {
+  UNIMPLEMENTED();
+}
+
+
+void AssemblerMacros::EnterStubFrame(Assembler* assembler) {
+  UNIMPLEMENTED();
+}
+
+}  // namespace dart
+
+#endif  // defined TARGET_ARCH_ARM
+