[builtins] Introduce proper Float64Exp operator.

src/crankshaft/mips64/lithium-mips64.h

Index: src/crankshaft/mips64/lithium-mips64.h
diff --git a/src/crankshaft/mips64/lithium-mips64.h b/src/crankshaft/mips64/lithium-mips64.h
index 5d282ec7aa9f72886e83ce2eb79adeddfa5e04ad..cc44ae6f436d1ef6f632737380889c72eb903f58 100644
--- a/src/crankshaft/mips64/lithium-mips64.h
+++ b/src/crankshaft/mips64/lithium-mips64.h
@@ -900,24 +900,11 @@ class LMathClz32 final : public LTemplateInstruction<1, 1, 0> {
   DECLARE_CONCRETE_INSTRUCTION(MathClz32, "math-clz32")
 };
 
-
-class LMathExp final : public LTemplateInstruction<1, 1, 3> {
+class LMathExp final : public LTemplateInstruction<1, 1, 0> {
  public:
-  LMathExp(LOperand* value,
-           LOperand* double_temp,
-           LOperand* temp1,
-           LOperand* temp2) {
-    inputs_[0] = value;
-    temps_[0] = temp1;
-    temps_[1] = temp2;
-    temps_[2] = double_temp;
-    ExternalReference::InitializeMathExpData();
-  }
+  explicit LMathExp(LOperand* value) { inputs_[0] = value; }
 
   LOperand* value() { return inputs_[0]; }
-  LOperand* temp1() { return temps_[0]; }
-  LOperand* temp2() { return temps_[1]; }
-  LOperand* double_temp() { return temps_[2]; }
 
   DECLARE_CONCRETE_INSTRUCTION(MathExp, "math-exp")
 };