Make the runtime entry for setting/changing accessors "atomic".

src/arm/full-codegen-arm.cc

Index: src/arm/full-codegen-arm.cc
diff --git a/src/arm/full-codegen-arm.cc b/src/arm/full-codegen-arm.cc
index 8639698051041118a6eb108706dde664df16ff80..303f0b086e7ed815e22f34d472e7d77bd6a0d268 100644
--- a/src/arm/full-codegen-arm.cc
+++ b/src/arm/full-codegen-arm.cc
@@ -1498,11 +1498,15 @@ void FullCodeGenerator::VisitObjectLiteral(ObjectLiteral* expr) {
         __ ldr(r0, MemOperand(sp));
         __ push(r0);
         VisitForStackValue(key);
-        __ mov(r1, Operand(property->kind() == ObjectLiteral::Property::SETTER ?
-                           Smi::FromInt(1) :
-                           Smi::FromInt(0)));
-        __ push(r1);
-        VisitForStackValue(value);
+        if (property->kind() == ObjectLiteral::Property::GETTER) {
+          VisitForStackValue(value);
+          __ LoadRoot(r1, Heap::kNullValueRootIndex);
+          __ push(r1);
+        } else {
+          __ LoadRoot(r1, Heap::kNullValueRootIndex);
+          __ push(r1);
+          VisitForStackValue(value);
+        }
         __ mov(r0, Operand(Smi::FromInt(NONE)));
         __ push(r0);
         __ CallRuntime(Runtime::kDefineOrRedefineAccessorProperty, 5);