[builtins] Introduce proper Float64Tan operator.

src/crankshaft/arm64/lithium-arm64.h

Index: src/crankshaft/arm64/lithium-arm64.h
diff --git a/src/crankshaft/arm64/lithium-arm64.h b/src/crankshaft/arm64/lithium-arm64.h
index 0a7c4523785665d96f8bbea11dc08f8ff7d97790..7f2ac23fef9caabd43dd69c9afce470aa7e42cea 100644
--- a/src/crankshaft/arm64/lithium-arm64.h
+++ b/src/crankshaft/arm64/lithium-arm64.h
@@ -57,7 +57,6 @@ class LCodeGen;
   V(ConstantI)                               \
   V(ConstantS)                               \
   V(ConstantT)                               \
-  V(ConstructDouble)                         \
   V(Context)                                 \
   V(DebugBreak)                              \
   V(DeclareGlobals)                          \
@@ -995,20 +994,6 @@ class LDoubleBits final : public LTemplateInstruction<1, 1, 0> {
 };
 
 
-class LConstructDouble final : public LTemplateInstruction<1, 2, 0> {
- public:
-  LConstructDouble(LOperand* hi, LOperand* lo) {
-    inputs_[0] = hi;
-    inputs_[1] = lo;
-  }
-
-  LOperand* hi() { return inputs_[0]; }
-  LOperand* lo() { return inputs_[1]; }
-
-  DECLARE_CONCRETE_INSTRUCTION(ConstructDouble, "construct-double")
-};
-
-
 class LClassOfTestAndBranch final : public LControlInstruction<1, 2> {
  public:
   LClassOfTestAndBranch(LOperand* value, LOperand* temp1, LOperand* temp2) {