X87: [builtins] Introduce proper Float64Exp operator.

src/crankshaft/x87/lithium-x87.h

Index: src/crankshaft/x87/lithium-x87.h
diff --git a/src/crankshaft/x87/lithium-x87.h b/src/crankshaft/x87/lithium-x87.h
index 98703aecd77d53704389558f8761f945991130be..22af3f935c2d29a37abff11023b8998668cf957f 100644
--- a/src/crankshaft/x87/lithium-x87.h
+++ b/src/crankshaft/x87/lithium-x87.h
@@ -904,21 +904,11 @@ class LMathClz32 final : public LTemplateInstruction<1, 1, 0> {
   DECLARE_CONCRETE_INSTRUCTION(MathClz32, "math-clz32")
 };
 
-
-class LMathExp final : public LTemplateInstruction<1, 1, 2> {
+class LMathExp final : public LTemplateInstruction<1, 1, 0> {
  public:
-  LMathExp(LOperand* value,
-           LOperand* temp1,
-           LOperand* temp2) {
-    inputs_[0] = value;
-    temps_[0] = temp1;
-    temps_[1] = temp2;
-    ExternalReference::InitializeMathExpData();
-  }
+  explicit LMathExp(LOperand* value) { inputs_[0] = value; }
 
   LOperand* value() { return inputs_[0]; }
-  LOperand* temp1() { return temps_[0]; }
-  LOperand* temp2() { return temps_[1]; }
 
   DECLARE_CONCRETE_INSTRUCTION(MathExp, "math-exp")
 };