added initial GLSL support to skslc

src/sksl/ast/SkSLASTNode.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_ASTNODE
 #define SKSL_ASTNODE
 
 #include <memory>
 #include <string>
 
 namespace SkSL {
 
 /**
  * Represents a node in the abstract syntax tree (AST). The AST is based directly on the parse tree;
  * it is a parsed-but-not-yet-analyzed version of the program.
  */
 struct ASTNode {
     virtual ~ASTNode() {}
-        
+     
     virtual std::string description() const = 0;
 };
 
 } // namespace
 
 #endif