Revert of SkSL performance improvements

src/sksl/ir/SkSLFunctionReference.h

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
  
 #ifndef SKSL_FUNCTIONREFERENCE
 #define SKSL_FUNCTIONREFERENCE
 
 #include "SkSLExpression.h"
 
 namespace SkSL {
 
 /**
  * An identifier referring to a function name. This is an intermediate value: FunctionReferences are 
  * always eventually replaced by FunctionCalls in valid programs.
  */
 struct FunctionReference : public Expression {
-    FunctionReference(Position position, std::vector<const FunctionDeclaration*> function)
-    : INHERITED(position, kFunctionReference_Kind, *kInvalid_Type)
+    FunctionReference(Position position, std::vector<std::shared_ptr<FunctionDeclaration>> function)
+    : INHERITED(position, kFunctionReference_Kind, kInvalid_Type)
     , fFunctions(function) {}
 
     virtual std::string description() const override {
         ASSERT(false);
         return "<function>";
     }
 
-    const std::vector<const FunctionDeclaration*> fFunctions;
+    const std::vector<std::shared_ptr<FunctionDeclaration>> fFunctions;
 
     typedef Expression INHERITED;
 };
 
 } // namespace
 
 #endif