Fix missing write barrier in store field stub.

src/mips/lithium-mips.cc

Index: src/mips/lithium-mips.cc
diff --git a/src/mips/lithium-mips.cc b/src/mips/lithium-mips.cc
index 49a462ae15be05a01faf2323605ed9bb529743cc..d0f86cd9e184f6af113441bfdae9aae5c55766e1 100644
--- a/src/mips/lithium-mips.cc
+++ b/src/mips/lithium-mips.cc
@@ -2046,16 +2046,28 @@ LInstruction* LChunkBuilder::DoTransitionElementsKind(
 
 LInstruction* LChunkBuilder::DoStoreNamedField(HStoreNamedField* instr) {
   bool needs_write_barrier = instr->NeedsWriteBarrier();
-
-  LOperand* obj = needs_write_barrier
-      ? UseTempRegister(instr->object())
-      : UseRegisterAtStart(instr->object());
+  bool needs_write_barrier_for_map = !instr->transition().is_null() &&
+      instr->NeedsWriteBarrierForMap();
+
+  LOperand* obj;
+  if (needs_write_barrier) {
+    obj = instr->is_in_object()
+        ? UseRegister(instr->object())
+        : UseTempRegister(instr->object());
+  } else {
+    obj = needs_write_barrier_for_map
+        ? UseRegister(instr->object())
+        : UseRegisterAtStart(instr->object());
+  }
 
   LOperand* val = needs_write_barrier
       ? UseTempRegister(instr->value())
       : UseRegister(instr->value());
 
-  return new(zone()) LStoreNamedField(obj, val);
+  // We need a temporary register for write barrier of the map field.
+  LOperand* temp = needs_write_barrier_for_map ? TempRegister() : NULL;
+
+  return new(zone()) LStoreNamedField(obj, val, temp);
 }