[builtins] Introduce proper Float64Atan and Float64Atan2 operators.

src/compiler/mips64/instruction-selector-mips64.cc

Index: src/compiler/mips64/instruction-selector-mips64.cc
diff --git a/src/compiler/mips64/instruction-selector-mips64.cc b/src/compiler/mips64/instruction-selector-mips64.cc
index abcde813d10470fe21ccce6adc0c8da3d1ea8b00..50a14abe4809ccd93bc62cd5d91d93e26b294358 100644
--- a/src/compiler/mips64/instruction-selector-mips64.cc
+++ b/src/compiler/mips64/instruction-selector-mips64.cc
@@ -1340,6 +1340,14 @@ void InstructionSelector::VisitFloat32Neg(Node* node) { UNREACHABLE(); }
 
 void InstructionSelector::VisitFloat64Neg(Node* node) { UNREACHABLE(); }
 
+void InstructionSelector::VisitFloat64Ieee754Binop(Node* node,
+                                                   InstructionCode opcode) {
+  Mips64OperandGenerator g(this);
+  Emit(opcode, g.DefineAsFixed(node, f0), g.UseFixed(node->InputAt(0), f12),
+       g.UseFixed(node->InputAt(1), f14))
+      ->MarkAsCall();
+}
+
 void InstructionSelector::VisitFloat64Ieee754Unop(Node* node,
                                                   InstructionCode opcode) {
   Mips64OperandGenerator g(this);