Update the README and test2.gif.

README.md

 `test` provides a standard way of writing and running tests in Dart.
 
 ## Writing Tests
 
 Tests are specified using the top-level [`test()`][test] function, and test
 assertions are made using [`expect()`][expect]:
 
 [test]: http://www.dartdocs.org/documentation/test/latest/index.html#test/test@id_test
 [expect]: http://www.dartdocs.org/documentation/test/latest/index.html#test/test@id_expect
 
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   });
 }
 ```
 
 ## Running Tests
 
 A single test file can be run just using `dart path/to/test.dart`.
 
 ![Tests being run via "dart path/to/test.dart".](https://raw.githubusercontent.com/dart-lang/test/master/image/test1.gif)
 
-Many tests can be run at a time using `pub run test:test path/to/dir`.
+Many tests can be run at a time using `pub run test:test path/to/dir` (on Dart
+1.10, this can be shortened to `pub run test path/to/dir`).
 
 ![Directory being run via "pub run".](https://raw.githubusercontent.com/dart-lang/test/master/image/test2.gif)
 
 `test` considers any file that ends with `_test.dart` to be a test file. If
 you don't pass any paths, it will run all the test files in your `test/`
 directory, making it easy to test your entire application at once.
 
 By default, tests are run in the Dart VM, but you can run them in the browser as
 well by passing `pub run test:test -p chrome path/to/test.dart`.
 `test` will take care of starting the browser and loading the tests, and all
@@ skipping 34 matching lines @@
 Platform selectors can contain identifiers, parentheses, and operators. When
 loading a test, each identifier is set to `true` or `false` based on the current
 platform, and the test is only loaded if the platform selector returns `true`.
 The operators `||`, `&&`, `!`, and `? :` all work just like they do in Dart. The
 valid identifiers are:
 
 * `vm`: Whether the test is running on the command-line Dart VM.
 
 * `chrome`: Whether the test is running on Google Chrome.
 
+* `firefox`: Whether the test is running on Mozilla Firefox.
+
 * `dart-vm`: Whether the test is running on the Dart VM in any context. For now
   this is identical to `vm`, but it will also be true for Dartium in the future.
   It's identical to `!js`.
 
 * `browser`: Whether the test is running in any browser.
 
 * `js`: Whether the test has been compiled to JS. This is identical to
   `!dart-vm`.
 
 * `blink`: Whether the test is running in a browser that uses the Blink
@@ skipping 122 matching lines @@
 ```shell
 $ pub serve
 Loading source assets...
 Loading test/pub_serve transformers...
 Serving my_app web on http://localhost:8080
 Serving my_app test on http://localhost:8081
 Build completed successfully
 ```
 
 In this case, the port is `8081`. In another terminal, pass this port to
-`--pub-serve` and otherwise invoke `pub run test` as normal:
+`--pub-serve` and otherwise invoke `pub run test:test` as normal:
 
 ```shell
-$ pub run test --pub-serve=8081 -p chrome
+$ pub run test:test --pub-serve=8081 -p chrome
 "pub serve" is compiling test/my_app_test.dart...
 "pub serve" is compiling test/utils_test.dart...
 00:00 +42: All tests passed!
 ```