Rename mojo_html_viewer target to just html_viewer.

mojo/mojo.gyp

 # Copyright 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 {
   'target_defaults': {
     'conditions': [
       ['mojo_shell_debug_url != ""', {
         'defines': [
           'MOJO_SHELL_DEBUG=1',
           'MOJO_SHELL_DEBUG_URL="<(mojo_shell_debug_url)"',
          ],
       }],
     ],
   },
   'includes': [
     'mojo_apps.gypi',
     'mojo_converters.gypi',
     'mojo_services.gypi',
     'mojo_variables.gypi',
   ],
   'targets': [
     {
       # GN version: //mojo
       'target_name': 'mojo',
       'type': 'none',
       'dependencies': [
         'edk/mojo_edk.gyp:mojo_edk',
+        'html_viewer',
         'mojo_application_manager',
         'mojo_application_manager_unittests',
         'mojo_apps_js_unittests',
         'mojo_base.gyp:mojo_base',
         'mojo_clipboard',
         'mojo_clipboard_unittests',
         'mojo_geometry_lib',
-        'mojo_html_viewer',
         'mojo_input_events_lib',
         'mojo_js_content_handler',
         'mojo_js_standalone',
         'mojo_js_unittests',
         'mojo_native_viewport_service',
         'mojo_network_service',
         'mojo_shell',
         'mojo_shell_lib',
         'mojo_shell_tests',
         'mojo_surfaces_lib',
@@ skipping 679 matching lines @@
             '../build/isolate.gypi',
           ],
           'sources': [
             'mojo_js_unittests.isolate',
           ],
         },
       ],
     }],
   ],
 }