Stoppp using trippple consonants

pkg/testing/README.md

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 # Test Infrastructure without Batteries
 
 This package:
 
   * Provides a way to test a compiler in multiple steps.
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 A suite is expected to implement a subclass of `ChainContext` which defines the steps that make up the chain and return it from `createContext`.
 
 A step is a subclass of `Step`. The input to the first step is a `TestDescription`. The input to step n+1 is the output of step n.
 
 Here is an example of a suite that runs tests on the Dart VM:
 
 ```dart
 import 'testing.dart';
 
 Future<ChainContext> createContext(
-    Chain suite, Map<String, String> enviroment) async {
+    Chain suite, Map<String, String> environment) async {
   return new VmContext();
 }
 
 class VmContext extends ChainContext {
   final List<Step> steps = const <Step>[const DartVmStep()];
 }
 
 class DartVmStep extends Step<TestDescription, int, VmContext> {
   const DartVmStep();
 
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 To run the suite `my_suite` from `package:test`, create a file named `mysuite_test.dart` with this content:
 
     import 'package:test/test.dart' show Timeout, test;
 
     import 'package:testing/testing.dart' show run;
 
     main() {
       test("my_suite", () => run([], ["my_suite"]),
           timeout: new Timeout(new Duration(minutes: 5)));
     }