ARM: Implement correct rounding in the lithium codegenerator.

src/arm/lithium-arm.cc

Index: src/arm/lithium-arm.cc
diff --git a/src/arm/lithium-arm.cc b/src/arm/lithium-arm.cc
index f179865348fddcedd958f933770088f520426081..a79ebb834aba0d97b9cb2e9ae9ee1432d27f374c 100644
--- a/src/arm/lithium-arm.cc
+++ b/src/arm/lithium-arm.cc
@@ -1219,7 +1219,9 @@ LInstruction* LChunkBuilder::DoUnaryMathOperation(HUnaryMathOperation* instr) {
     return MarkAsCall(DefineFixedDouble(result, d2), instr);
   } else {
     LOperand* input = UseRegisterAtStart(instr->value());
-    LOperand* temp = (op == kMathFloor) ? TempRegister() : NULL;
+    LOperand* temp = (op == kMathFloor || op == kMathRound)
+        ? TempRegister()
+        : NULL;
     LUnaryMathOperation* result = new LUnaryMathOperation(input, temp);
     switch (op) {
       case kMathAbs: