Fix typos (#12367)
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 7823b66..9d0adf1 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -125,7 +125,7 @@
Working with flutter tools
--------------------------
-The flutter tools itself is built when you run `flutter` for the first time and each time
+The flutter tool itself is built when you run `flutter` for the first time and each time
you run `flutter upgrade`. If you want to alter and re-test the tool's behavior itself,
locally commit your tool changes in git and the tool will be rebuilt from Dart sources
in `packages/flutter_tools` the next time you run `flutter`.
@@ -189,8 +189,8 @@
We grant commit access to people who have gained our trust and demonstrated
a commitment to Flutter.
-Tools for tracking an improving test coverage
----------------------------------------------
+Tools for tracking and improving test coverage
+----------------------------------------------
We strive for a high degree of test coverage for the Flutter framework. We use
Coveralls to [track our test coverage](https://coveralls.io/github/flutter/flutter?branch=master).
