Remove scratch register requirement from LoadInstanceDescriptors on arm and mips.

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 4a6a1fdc437d538fe7ff204808403b7b8c7d7bce..0b6dcaea51eeef24192f5573750a2749d2a27258 100644
--- a/src/mips/lithium-mips.cc
+++ b/src/mips/lithium-mips.cc
@@ -2234,9 +2234,7 @@ LInstruction* LChunkBuilder::DoForInPrepareMap(HForInPrepareMap* instr) {
 
 LInstruction* LChunkBuilder::DoForInCacheArray(HForInCacheArray* instr) {
   LOperand* map = UseRegister(instr->map());
-  LOperand* scratch = TempRegister();
-  return AssignEnvironment(DefineAsRegister(
-      new(zone()) LForInCacheArray(map, scratch)));
+  return AssignEnvironment(DefineAsRegister(new(zone()) LForInCacheArray(map)));
 }