Fix missing write barrier in store field stub.

src/arm/lithium-codegen-arm.cc

Index: src/arm/lithium-codegen-arm.cc
diff --git a/src/arm/lithium-codegen-arm.cc b/src/arm/lithium-codegen-arm.cc
index fd4b3e84085509a352f9f3fed4805585bfcb0549..a360334df49bb2f38ef6207b573c79d5e529ffd9 100644
--- a/src/arm/lithium-codegen-arm.cc
+++ b/src/arm/lithium-codegen-arm.cc
@@ -3675,6 +3675,18 @@ void LCodeGen::DoStoreNamedField(LStoreNamedField* instr) {
   if (!instr->transition().is_null()) {
     __ mov(scratch, Operand(instr->transition()));
     __ str(scratch, FieldMemOperand(object, HeapObject::kMapOffset));
+    if (instr->hydrogen()->NeedsWriteBarrierForMap()) {
+      Register temp = ToRegister(instr->TempAt(0));
+      // Update the write barrier for the map field.
+      __ RecordWriteField(object,
+                          HeapObject::kMapOffset,
+                          scratch,
+                          temp,
+                          kLRHasBeenSaved,
+                          kSaveFPRegs,
+                          OMIT_REMEMBERED_SET,
+                          OMIT_SMI_CHECK);
+    }
   }
 
   // Do the store.