declare const instead of var

Closes #22

Author: danieljuhl

index.js

@@ -6,7 +6,7 @@ const LineDiff = require('line-diff');
 const bannerMessage =
   '// This file is automatically generated.\n// Please do not change this file!';
 
-const cssModuleExport = 'declare var cssExports: CssExports;\nexport = cssExports;\n';
+const cssModuleExport = 'declare const cssExports: CssExports;\nexport = cssExports;\n';
 
 const getNoDeclarationFileError = ({ filename }) =>
   new Error(