refactored SkSL VarDeclaration handling

src/sksl/ast/SkSLASTInterfaceBlock.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_ASTINTERFACEBLOCK
 #define SKSL_ASTINTERFACEBLOCK
 
 #include "SkSLASTVarDeclaration.h"
 
 namespace SkSL {
 
 /**
  * An interface block, as in:
  *
  * out gl_PerVertex {
  *   layout(builtin=0) vec4 gl_Position;
  *   layout(builtin=1) float gl_PointSize;
  * };
  */
 struct ASTInterfaceBlock : public ASTDeclaration {
     // valueName is empty when it was not present in the source
     ASTInterfaceBlock(Position position,
                       ASTModifiers modifiers, 
                       std::string interfaceName, 
                       std::string valueName, 
-                      std::vector<std::unique_ptr<ASTVarDeclaration>> declarations)
+                      std::vector<std::unique_ptr<ASTVarDeclarations>> declarations)
     : INHERITED(position, kInterfaceBlock_Kind)
     , fModifiers(modifiers)
     , fInterfaceName(std::move(interfaceName))
     , fValueName(std::move(valueName))
     , fDeclarations(std::move(declarations)) {}
 
     std::string description() const override {
         std::string result = fModifiers.description() + fInterfaceName + " {\n";
         for (size_t i = 0; i < fDeclarations.size(); i++) {
             result += fDeclarations[i]->description() + "\n";
         }
         result += "}";
         if (fValueName.length()) {
             result += " " + fValueName;
         }
         return result + ";";
     }
 
     const ASTModifiers fModifiers;
     const std::string fInterfaceName;
     const std::string fValueName;
-    const std::vector<std::unique_ptr<ASTVarDeclaration>> fDeclarations;
+    const std::vector<std::unique_ptr<ASTVarDeclarations>> fDeclarations;
 
     typedef ASTDeclaration INHERITED;
 };
 
 } // namespace
 
 #endif