Implement write barrier on ARM.

runtime/vm/dart_entry_test.cc

 // 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.
 
 #include "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/class_finalizer.h"
 #include "vm/compiler.h"
 #include "vm/dart_entry.h"
 #include "vm/object.h"
 #include "vm/resolver.h"
 #include "vm/symbols.h"
 #include "vm/unit_test.h"
 
 namespace dart {
 
-// Only ia32 and x64 can run execution tests.
-#if defined(TARGET_ARCH_IA32) || defined(TARGET_ARCH_X64)
+// Only IA32, X64, and ARM can run execution tests.
+#if defined(TARGET_ARCH_IA32) ||                                               \
+    defined(TARGET_ARCH_X64) ||                                                \
+    defined(TARGET_ARCH_ARM)
 
 TEST_CASE(DartEntry) {
   const char* kScriptChars =
       "class A {\n"
       "  static foo() { return 42; }\n"
       "}\n";
   String& url = String::Handle(String::New("dart-test:DartEntry"));
   String& source = String::Handle(String::New(kScriptChars));
   Script& script = Script::Handle(Script::New(url,
                                               source,
@@ skipping 77 matching lines @@
   Function& function = Function::Handle(cls.LookupDynamicFunction(name));
   EXPECT(!function.IsNull());
   const Array& args = Array::Handle(Array::New(1));
   args.SetAt(0, instance);
   const Object& retval = Object::Handle(DartEntry::InvokeFunction(function,
                                                                   args));
   EXPECT(retval.IsError());
   EXPECT_SUBSTRING("++++", Error::Cast(retval).ToErrorCString());
 }
 
-#endif  // TARGET_ARCH_IA32 || TARGET_ARCH_X64.
+#endif  // TARGET_ARCH_IA32 || TARGET_ARCH_X64 || TARGET_ARCH_ARM
 
 }  // namespace dart