A64: Handle Smi representation in MathAbs and fix MathPowStub

src/a64/lithium-a64.cc

Index: src/a64/lithium-a64.cc
diff --git a/src/a64/lithium-a64.cc b/src/a64/lithium-a64.cc
index efc35f83e73f7ccccd8d3fa4d5eb6b0bedab60d7..e3c8c064c62acf51689b472f0e7752fe7e757a54 100644
--- a/src/a64/lithium-a64.cc
+++ b/src/a64/lithium-a64.cc
@@ -2345,7 +2345,7 @@ LInstruction* LChunkBuilder::DoUnaryMathOperation(HUnaryMathOperation* instr) {
   switch (instr->op()) {
     case kMathAbs: {
       Representation r = instr->representation();
-      if (r.IsTagged()) {
+      if (r.IsTagged() || r.IsSmi()) {
         // The tagged case might need to allocate a HeapNumber for the result,
         // so it is handled by a separate LInstruction.
         LOperand* input = UseRegister(instr->value());