added basic dataflow analysis to skslc

src/sksl/ir/SkSLIndexExpression.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_INDEX
 #define SKSL_INDEX
 
+#include "SkSLContext.h"
 #include "SkSLExpression.h"
 #include "SkSLUtil.h"
 
 namespace SkSL {
 
 /**
  * Given a type, returns the type that will result from extracting an array value from it.
  */
 static const Type& index_type(const Context& context, const Type& type) {
     if (type.kind() == Type::kMatrix_Kind) {
@@ skipping 35 matching lines @@
 
     const std::unique_ptr<Expression> fBase;
     const std::unique_ptr<Expression> fIndex;
 
     typedef Expression INHERITED;
 };
 
 } // namespace
 
 #endif