Fix some observatory analysis issues.

runtime/observatory/HACKING.md

 # Hacking Observatory
 
 These instructions will guide you through the Observatory development and
 testing workflow.
 
 ## SDK Setup & Build
 Getting ready to start.
 
 Before you start to hack on Observatory, follow the [instructions][build_sdk] to
 have a working environment in which you are able to build and test the Dart SDK.
 
 ### Develop with Dartium ~ Suggested
 If you want to avoid triggering a new compilation to JavaScript for each edit
 you do, you can use a modified version of Chromium named Dartium that will
-interpret you dart code directly.
+interpret your dart code directly.
 
 You can obtain Dartium in two different ways:
 1. [Download][download_dartium] the binaries
 2. [Build][build_dartium] Dartium from the source code
 
 
 ## Run existing tests
 Before hacking Observatory let's run the existing Observatory tests.
 We suggest to run all the test in __debug__ mode.
 
@@ skipping 158 matching lines @@
 ## Run your tests
 See: __Run existing tests__
 
 [build_sdk]: https://github.com/dart-lang/sdk/wiki/Building "Building the Dart SDK"
 [download_dartium]: https://webdev.dartlang.org/tools/dartium/ "Download Dartium"
 [build_dartium]: https://github.com/dart-lang/sdk/wiki/Building-Dartium "Build Dartium"
 [open_observatory]: http://localhost:8080/ "Open Observatory"
 [observatory_get_started]: https://dart-lang.github.io/observatory/get-started.html "Observatory get started"
 [code_review]: https://github.com/dart-lang/sdk/wiki/Code-review-workflow-with-GitHub-and-reitveld "Code Review"
 [test_library]: https://pub.dartlang.org/packages/test "Test Library"