[builtins] Introduce proper Float64Atan and Float64Atan2 operators.

src/compiler/instruction-selector.cc

Index: src/compiler/instruction-selector.cc
diff --git a/src/compiler/instruction-selector.cc b/src/compiler/instruction-selector.cc
index d99d2116e820d4272b4cdbd0fdeaec082a12a734..ec429d90b070a4cbda443cdf3332cfe3a4ac5554 100644
--- a/src/compiler/instruction-selector.cc
+++ b/src/compiler/instruction-selector.cc
@@ -1127,6 +1127,10 @@ void InstructionSelector::VisitNode(Node* node) {
       return MarkAsFloat64(node), VisitFloat64Max(node);
     case IrOpcode::kFloat64Abs:
       return MarkAsFloat64(node), VisitFloat64Abs(node);
+    case IrOpcode::kFloat64Atan:
+      return MarkAsFloat64(node), VisitFloat64Atan(node);
+    case IrOpcode::kFloat64Atan2:
+      return MarkAsFloat64(node), VisitFloat64Atan2(node);
     case IrOpcode::kFloat64Log:
       return MarkAsFloat64(node), VisitFloat64Log(node);
     case IrOpcode::kFloat64Log1p:
@@ -1236,6 +1240,14 @@ void InstructionSelector::VisitLoadParentFramePointer(Node* node) {
   Emit(kArchParentFramePointer, g.DefineAsRegister(node));
 }
 
+void InstructionSelector::VisitFloat64Atan(Node* node) {
+  VisitFloat64Ieee754Unop(node, kIeee754Float64Atan);
+}
+
+void InstructionSelector::VisitFloat64Atan2(Node* node) {
+  VisitFloat64Ieee754Binop(node, kIeee754Float64Atan2);
+}
+
 void InstructionSelector::VisitFloat64Log(Node* node) {
   VisitFloat64Ieee754Unop(node, kIeee754Float64Log);
 }