[builtins] Introduce proper Float64Tan operator.

src/crankshaft/arm/lithium-arm.cc

Index: src/crankshaft/arm/lithium-arm.cc
diff --git a/src/crankshaft/arm/lithium-arm.cc b/src/crankshaft/arm/lithium-arm.cc
index 03b05de98683ae70d05ae32cbe513f7470994dad..284185a7eb56be75e5aca4d37c7c18a3b53ffd3b 100644
--- a/src/crankshaft/arm/lithium-arm.cc
+++ b/src/crankshaft/arm/lithium-arm.cc
@@ -1987,13 +1987,6 @@ LInstruction* LChunkBuilder::DoDoubleBits(HDoubleBits* instr) {
 }
 
 
-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)