Use UniqueSet<T> and Unique<T> in HCheckMaps and HCheckValue.

src/mips/lithium-codegen-mips.cc

Index: src/mips/lithium-codegen-mips.cc
diff --git a/src/mips/lithium-codegen-mips.cc b/src/mips/lithium-codegen-mips.cc
index 42701b90292a14ca4840007b28b669033ce18b93..80c20512a050e9a78be660d83df6785bdcbce494 100644
--- a/src/mips/lithium-codegen-mips.cc
+++ b/src/mips/lithium-codegen-mips.cc
@@ -5092,7 +5092,7 @@ void LCodeGen::DoCheckInstanceType(LCheckInstanceType* instr) {
 
 void LCodeGen::DoCheckValue(LCheckValue* instr) {
   Register reg = ToRegister(instr->value());
-  Handle<HeapObject> object = instr->hydrogen()->object();
+  Handle<HeapObject> object = instr->hydrogen()->object().handle();
   AllowDeferredHandleDereference smi_check;
   if (isolate()->heap()->InNewSpace(*object)) {
     Register reg = ToRegister(instr->value());
@@ -5143,7 +5143,6 @@ void LCodeGen::DoCheckMaps(LCheckMaps* instr) {
   LOperand* input = instr->value();
   ASSERT(input->IsRegister());
   Register reg = ToRegister(input);
-  SmallMapList* map_set = instr->hydrogen()->map_set();
   __ lw(map_reg, FieldMemOperand(reg, HeapObject::kMapOffset));
 
   DeferredCheckMaps* deferred = NULL;
@@ -5152,12 +5151,13 @@ void LCodeGen::DoCheckMaps(LCheckMaps* instr) {
     __ bind(deferred->check_maps());
   }
 
+  UniqueSet<Map> map_set = instr->hydrogen()->map_set();
   Label success;
-  for (int i = 0; i < map_set->length() - 1; i++) {
-    Handle<Map> map = map_set->at(i);
+  for (int i = 0; i < map_set.size() - 1; i++) {
+    Handle<Map> map = map_set.at(i).handle();
     __ CompareMapAndBranch(map_reg, map, &success, eq, &success);
   }
-  Handle<Map> map = map_set->last();
+  Handle<Map> map = map_set.at(map_set.size() - 1).handle();
   // Do the CompareMap() directly within the Branch() and DeoptimizeIf().
   if (instr->hydrogen()->has_migration_target()) {
     __ Branch(deferred->entry(), ne, map_reg, Operand(map));