docs(dependency-injection): tweak Dart wording

Author: kwalrath

public/docs/ts/latest/guide/dependency-injection.jade

@@ -704,10 +704,13 @@ code-example(format, language="html").
     The injector resolves these tokens and injects the corresponding services into the matching factory function parameters.
 // #enddocregion providers-factory-4
 // #docregion providers-factory-5
+- var lang = current.path[1]
+- var anexportedvar = lang == 'dart' ? 'a constant' : 'an exported variable'
+- var variable = lang == 'dart' ? 'constant' : 'variable'
 :marked
-  Notice that we captured the factory provider in an exported variable, `heroServiceProvider`.
+  Notice that we captured the factory provider in #{anexportedvar}, `heroServiceProvider`.
   This extra step makes the factory provider reusable.
-  We can register our `HeroService` with this variable wherever we need it.
+  We can register our `HeroService` with this #{variable} wherever we need it.
 
   In our sample, we need it only in the `HeroesComponent`,
   where it replaces the previous `HeroService` registration in the metadata `providers` array.