[builtins] Introduce proper Float64Tan operator.

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

Index: src/crankshaft/arm/lithium-codegen-arm.cc
diff --git a/src/crankshaft/arm/lithium-codegen-arm.cc b/src/crankshaft/arm/lithium-codegen-arm.cc
index 3bd9a1e2b2251fc920d487a94d8f79e6eaa4696d..0ad814a672356d8a318cd83c23a2b604a3a4b6f7 100644
--- a/src/crankshaft/arm/lithium-codegen-arm.cc
+++ b/src/crankshaft/arm/lithium-codegen-arm.cc
@@ -5046,15 +5046,6 @@ void LCodeGen::DoDoubleBits(LDoubleBits* instr) {
 }
 
 
-void LCodeGen::DoConstructDouble(LConstructDouble* instr) {
-  Register hi_reg = ToRegister(instr->hi());
-  Register lo_reg = ToRegister(instr->lo());
-  DwVfpRegister result_reg = ToDoubleRegister(instr->result());
-  __ VmovHigh(result_reg, hi_reg);
-  __ VmovLow(result_reg, lo_reg);
-}
-
-
 void LCodeGen::DoAllocate(LAllocate* instr) {
   class DeferredAllocate final : public LDeferredCode {
    public: