Adding namespace to grammar

Namespace is now able to be parsed so I included the Google Chrome WebIDL to the `web_idl_files_test.dart` for now. Below is an example of what is passing. What is not able to be parsed is either another non-WebIDL standard extended attribute or a bug in the parser. Will need todo more research to figure it out. Stuff like 

```
  [inline_doc] dictionary LaunchItem {
    // FileEntry for the file.
    [instanceOf=FileEntry] object entry;

    // The MIME type of the file.
    DOMString type;
  };
```  

Will fail on `[instanceOf=FileEntry]` but not on `[instanceOf = FileEntry]` which makes me think that its a parser bug. 

Chrome WebIDL  

```
PASS: Test chrome idl files Testing test/../idl/alarms.idl
PASS: Test chrome idl files Testing test/../idl/app_current_window_internal.idl
ERROR: Test chrome idl files Testing test/../idl/app_runtime.idl
  Test failed: Caught line 12, character 17: unexpected 'F'.
ERROR: Test chrome idl files Testing test/../idl/app_window.idl
  Test failed: Caught line 17, character 16: expected string literal, got 'n'.
PASS: Test chrome idl files Testing test/../idl/audio.idl
PASS: Test chrome idl files Testing test/../idl/autotest_private.idl
PASS: Test chrome idl files Testing test/../idl/bluetooth.idl
ERROR: Test chrome idl files Testing test/../idl/braille_display_private.idl
  Test failed: Caught line 9, character 5: expected string literal, got 'l'.
ERROR: Test chrome idl files Testing test/../idl/desktop_capture.idl
  Test failed: Caught line 11, character 5: expected string literal, got 's'.
ERROR: Test chrome idl files Testing test/../idl/developer_private.idl
  Test failed: Caught line 11, character 5: expected string literal, got 'h'.
PASS: Test chrome idl files Testing test/../idl/diagnostics.idl
ERROR: Test chrome idl files Testing test/../idl/dial.idl
  Test failed: Caught line 25, character 5: expected string literal, got 'n'.
PASS: Test chrome idl files Testing test/../idl/dns.idl
ERROR: Test chrome idl files Testing test/../idl/downloads.idl
  Test failed: Caught line 7, character 14: unexpected 'd'.
ERROR: Test chrome idl files Testing test/../idl/downloads_internal.idl
  Test failed: Caught line 6, character 8: unexpected 't'.
PASS: Test chrome idl files Testing test/../idl/experimental_discovery.idl
PASS: Test chrome idl files Testing test/../idl/experimental_identity.idl
ERROR: Test chrome idl files Testing test/../idl/experimental_idltest.idl
  Test failed: Caught line 20, character 49: unexpected 'U'.
ERROR: Test chrome idl files Testing test/../idl/feedback_private.idl
  Test failed: Caught line 11, character 17: unexpected 'B'.
ERROR: Test chrome idl files Testing test/../idl/file_system.idl
  Test failed: Caught line 31, character 5: expected string literal, got 'o'.
PASS: Test chrome idl files Testing test/../idl/identity.idl
PASS: Test chrome idl files Testing test/../idl/identity_private.idl
PASS: Test chrome idl files Testing test/../idl/location.idl
PASS: Test chrome idl files Testing test/../idl/log_private.idl
ERROR: Test chrome idl files Testing test/../idl/mdns.idl
  Test failed: Caught line 32, character 22: unexpected 't'.
ERROR: Test chrome idl files Testing test/../idl/media_galleries.idl
  Test failed: Caught line 11, character 5: expected string literal, got 'n'.
PASS: Test chrome idl files Testing test/../idl/media_galleries_private.idl
PASS: Test chrome idl files Testing test/../idl/music_manager_private.idl
ERROR: Test chrome idl files Testing test/../idl/notifications.idl
  Test failed: Caught line 10, character 5: expected string literal, got 'b'.
ERROR: Test chrome idl files Testing test/../idl/power.idl
  Test failed: Caught line 10, character 5: expected string literal, got 's'.
PASS: Test chrome idl files Testing test/../idl/push_messaging.idl
ERROR: Test chrome idl files Testing test/../idl/recovery_private.idl
  Test failed: Caught line 26, character 5: expected string literal, got 'c'.
ERROR: Test chrome idl files Testing test/../idl/rtc_private.idl
  Test failed: Caught line 8, character 20: expected whitespace/comment or string literal, got 'c'.
ERROR: Test chrome idl files Testing test/../idl/serial.idl
  Test failed: Caught line 11, character 18: expected string literal, got 's'.
ERROR: Test chrome idl files Testing test/../idl/signed_in_devices.idl
  Test failed: Caught line 9, character 5: expected string literal, got 'w'.
ERROR: Test chrome idl files Testing test/../idl/socket.idl
  Test failed: Caught line 9, character 5: expected string literal, got 't'.
PASS: Test chrome idl files Testing test/../idl/sockets_udp.idl
ERROR: Test chrome idl files Testing test/../idl/sync_file_system.idl
  Test failed: Caught line 13, character 5: expected string literal, got 'a'.
PASS: Test chrome idl files Testing test/../idl/system_cpu.idl
PASS: Test chrome idl files Testing test/../idl/system_display.idl
ERROR: Test chrome idl files Testing test/../idl/system_indicator.idl
  Test failed: Caught line 11, character 8: expected whitespace/comment, identifier, '[' or spaces, got '?'.
PASS: Test chrome idl files Testing test/../idl/system_memory.idl
ERROR: Test chrome idl files Testing test/../idl/system_storage.idl
  Test failed: Caught line 12, character 5: expected string literal, got 'f'.
ERROR: Test chrome idl files Testing test/../idl/tab_capture.idl
  Test failed: Caught line 10, character 5: expected string literal, got 'p'.
ERROR: Test chrome idl files Testing test/../idl/usb.idl
  Test failed: Caught line 12, character 19: expected whitespace/comment or string literal, got 'i'.
```