Fix typos

Fixes #50184

Change-Id: If17f838d932171e30ef92d1bda8d4918e7e08a8f
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/263622
Reviewed-by: Lasse Nielsen <lrn@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Brian Wilkerson <brianwilkerson@google.com>

pkg/testing/README.md

@@ -195,7 +195,7 @@ The `Dart` suite makes certain assumptions about the tests it runs.
 
  * An asynchronous test returns a `Future` from its `main`.
 
- * Tests manages global state.
+ * Tests manage global state.
 
 All tests are imported into the same program as individual libraries, which is why they all must use the same `.packages` file. The tests aren't concatenated, so they have the lexical scope you'd normally expect from a Dart library.
 

pkg/testing/lib/src/chain.dart

@@ -342,7 +342,7 @@ abstract class Step<I, O, C extends ChainContext> {
   /// the next step is executed by the now-ending step.
   ///
   /// When isAsync is false each step returns a future which is awaited,
-  /// effectivly meaning that only a single test is run at a time.
+  /// effectively meaning that only a single test is run at a time.
   ///
   /// When isAsync is true that step doesn't return a future (but adds it's
   /// future to a list which is awaited before sending an 'entire suite done'

pkg/testing/lib/src/expectation.dart

@@ -98,7 +98,7 @@ class ExpectationSet {
             break;
 
           default:
-            throw "Unrecoginized key: '$key' in '$map'.";
+            throw "Unrecognized key: '$key' in '$map'.";
         }
       });
       if (name == null) {