Use the same registers for StoreIC and KeyedStoreIC.

src/arm/stub-cache-arm.cc

Index: src/arm/stub-cache-arm.cc
diff --git a/src/arm/stub-cache-arm.cc b/src/arm/stub-cache-arm.cc
index 98002dc6688c3f4397427bfc855b5f98cb3617e4..1898dbc6fb2704c9fee39495c8eff4fde57d90c8 100644
--- a/src/arm/stub-cache-arm.cc
+++ b/src/arm/stub-cache-arm.cc
@@ -1294,10 +1294,11 @@ Register* StoreStubCompiler::registers() {
 
 
 Register* KeyedStoreStubCompiler::registers() {
-  // receiver, name, scratch1, scratch2, scratch3.
+  // receiver, name, scratch1/map, scratch2, scratch3.
   Register receiver = KeyedStoreIC::ReceiverRegister();
   Register name = KeyedStoreIC::NameRegister();
-  static Register registers[] = { receiver, name, r3, r4, r5 };
+  Register map = KeyedStoreIC::MapRegister();
+  static Register registers[] = { receiver, name, map, r4, r5 };
   return registers;
 }
 
@@ -1397,7 +1398,10 @@ Handle<Code> BaseLoadStoreStubCompiler::CompilePolymorphicIC(
   Label* smi_target = IncludesNumberType(types) ? &number_case : &miss;
   __ JumpIfSmi(receiver(), smi_target);
 
+  // Polymorphic keyed stores may use the map register
   Register map_reg = scratch1();
+  ASSERT(kind() != Code::KEYED_STORE_IC ||
+         map_reg.is(KeyedStoreIC::MapRegister()));
 
   int receiver_count = types->length();
   int number_of_handled_maps = 0;