docs(toh-1/dart): minor edits (#1614)

- Fixed HTML.
- Removed unnecessary snippet since it is in the code.
- Copyedit (Hero Property) -> (Hero property).

Author: chalin

public/docs/_examples/toh-1/dart-snippets/app_component_snippets_pt1.dart

@@ -25,7 +25,7 @@ template: '''
   <div><label>id: </label>{{hero.id}}</div>
   <div>
     <label>name: </label>
-    <div><input value="{{hero.name}}" placeholder="name"></div>
+    <input value="{{hero.name}}" placeholder="name">
   </div>'''
 // #enddocregion editing-Hero
 
@@ -35,7 +35,3 @@ class AppComponent {
   Hero hero = 'Windstorm';
 }
 // #enddocregion app-component-1
-
-// #docregion hero-property-1
-Hero hero = new Hero(1, 'Windstorm');
-// #enddocregion hero-property-1

public/docs/_examples/toh-1/dart/lib/app_component.dart

@@ -18,11 +18,13 @@ class Hero {
       <div><label>id: </label>{{hero.id}}</div>
       <div>
         <label>name: </label>
-        <div><input [(ngModel)]="hero.name" placeholder="name"></div>
+        <input [(ngModel)]="hero.name" placeholder="name">
       </div>'''
 )
 class AppComponent {
   String title = 'Tour of Heroes';
+  // #docregion hero-property-1
   Hero hero = new Hero(1, 'Windstorm');
+  // #enddocregion hero-property-1
 }
 // #enddocregion pt1

public/docs/_examples/toh-1/dart/web/main.dart

@@ -3,7 +3,7 @@ import 'package:angular2/platform/browser.dart';
 
 import 'package:angular2_tour_of_heroes/app_component.dart';
 
-main() {
+void main() {
   bootstrap(AppComponent);
 }
 // #enddocregion pt1

public/docs/dart/latest/tutorial/toh-pt1.jade

@@ -87,7 +87,7 @@ code-example(format="" language="bash").
   Now that we have a `Hero` class, let’s refactor our component’s `hero` property to be of type `Hero`.
   Then initialize it with an id of `1` and the name, "Windstorm".
 
-+makeExample('toh-1/dart-snippets/app_component_snippets_pt1.dart', 'hero-property-1', 'app_component.dart (Hero property)')(format=".")
++makeExample('toh-1/dart/lib/app_component.dart', 'hero-property-1', 'app_component.dart (hero property)')(format=".")
 
 :marked
   Because we changed the hero from a string to an object,