MIPS[64]: Fix `MIPS: Improve Float(32|64)(Max|Min)`.

src/crankshaft/mips/lithium-codegen-mips.cc

Index: src/crankshaft/mips/lithium-codegen-mips.cc
diff --git a/src/crankshaft/mips/lithium-codegen-mips.cc b/src/crankshaft/mips/lithium-codegen-mips.cc
index dfd605bb5f241457d8517db0f114ad168a04e4f2..93dca9552e0570759d73a0c4b72acd6ed77d4e5f 100644
--- a/src/crankshaft/mips/lithium-codegen-mips.cc
+++ b/src/crankshaft/mips/lithium-codegen-mips.cc
@@ -1766,7 +1766,9 @@ void LCodeGen::DoMathMinMax(LMathMinMax* instr) {
     FPURegister result_reg = ToDoubleRegister(instr->result());
 
     Label nan, done;
-    if (operation == HMathMinMax::kMathMax) {
+    if (left_reg.is(right_reg)) {
+      __ Move(result_reg, left_reg);
+    } else if (operation == HMathMinMax::kMathMax) {
       __ Float64Max(result_reg, left_reg, right_reg, &nan);
     } else {
       DCHECK(operation == HMathMinMax::kMathMin);