[builtins] Unify Atanh, Cbrt and Expm1 as exports from flibm.

src/compiler/js-builtin-reducer.h

Index: src/compiler/js-builtin-reducer.h
diff --git a/src/compiler/js-builtin-reducer.h b/src/compiler/js-builtin-reducer.h
index 79265f2b8c9926a4df117f8d681a437a9c27d0c4..10d85f176a5c8f27b5c342111f3fd805d513bbb1 100644
--- a/src/compiler/js-builtin-reducer.h
+++ b/src/compiler/js-builtin-reducer.h
@@ -31,6 +31,7 @@ class JSBuiltinReducer final : public AdvancedReducer {
  private:
   Reduction ReduceMathAtan(Node* node);
   Reduction ReduceMathAtan2(Node* node);
+  Reduction ReduceMathAtanh(Node* node);
   Reduction ReduceMathCeil(Node* node);
   Reduction ReduceMathClz32(Node* node);
   Reduction ReduceMathExp(Node* node);
@@ -43,6 +44,8 @@ class JSBuiltinReducer final : public AdvancedReducer {
   Reduction ReduceMathLog10(Node* node);
   Reduction ReduceMathMax(Node* node);
   Reduction ReduceMathMin(Node* node);
+  Reduction ReduceMathCbrt(Node* node);
+  Reduction ReduceMathExpm1(Node* node);
   Reduction ReduceMathRound(Node* node);
   Reduction ReduceMathSqrt(Node* node);
   Reduction ReduceMathTrunc(Node* node);