PPC/s390: [builtins] Introduce proper Float64Tan operator.

src/crankshaft/s390/lithium-s390.cc

Index: src/crankshaft/s390/lithium-s390.cc
diff --git a/src/crankshaft/s390/lithium-s390.cc b/src/crankshaft/s390/lithium-s390.cc
index ae75e9dfd3d2aa48fc507ee6d639a7ccd27b7df9..95fc126831e0e95660cf9380f2e2ae7add21c5d7 100644
--- a/src/crankshaft/s390/lithium-s390.cc
+++ b/src/crankshaft/s390/lithium-s390.cc
@@ -1793,12 +1793,6 @@ LInstruction* LChunkBuilder::DoDoubleBits(HDoubleBits* instr) {
   return DefineAsRegister(new (zone()) LDoubleBits(UseRegister(value)));
 }
 
-LInstruction* LChunkBuilder::DoConstructDouble(HConstructDouble* instr) {
-  LOperand* lo = UseRegister(instr->lo());
-  LOperand* hi = UseRegister(instr->hi());
-  return DefineAsRegister(new (zone()) LConstructDouble(hi, lo));
-}
-
 LInstruction* LChunkBuilder::DoReturn(HReturn* instr) {
   LOperand* context = info()->IsStub() ? UseFixed(instr->context(), cp) : NULL;
   LOperand* parameter_count = UseRegisterOrConstant(instr->parameter_count());