Fix typo in CHANGELOG.

CHANGELOG.md

 ## 1.23.0
 
 ### Core library changes
 * `dart:core`: Add `Uri.isScheme` function to check the scheme of a URI.
    Example: `uri.isScheme("http")`. Ignores case when comparing.
-    
+
 ## 1.22.0
 
 ### Language
 
   * Breaking change: ['Generalized tear-offs'](https://github.com/gbracha/generalizedTearOffs/blob/master/proposal.md)
     are no longer supported, and will cause errors. We updated the language spec
     and added warnings in 1.21, and are now taking the last step to fully
     de-support them. They were previously only supported in the VM, and there
     are almost no known uses of them in the wild.
 
@@ skipping 58 matching lines @@
 
     class Orca extends Predator {
       void chaseAndEat(Seal s) => ...
     }
     ```
 
     This isn't statically safe, because you could do:
 
     ```dart
     Predator predator = new Cat(); // Upcast.
-    predator(new Seal()); // Cats can't eat seals!
+    predator.chaseAndEat(new Seal()); // Cats can't eat seals!
     ```
 
     To preserve soundness in strong mode, in the body of a method that uses a
     covariant override (here, `Cat.chaseAndEat()`), the compiler automatically
     inserts a check that the parameter is of the expected type. So the compiler
     gives you something like:
 
     ```dart
     class Cat extends Predator {
       void chaseAndEat(o) {
@@ skipping 1573 matching lines @@
     they will keep the Dart process alive until they time out. This fixes the
     handling of persistent connections. Previously, the client would shut down
     immediately after a request.
 
   * **Breaking change:** `HttpServer` no longer compresses all traffic by
     default. The new `autoCompress` property can be set to `true` to re-enable
     compression.
 
 * `dart:isolate`: `Isolate.spawnUri` added the optional `packageRoot` argument,
   which controls how it resolves `package:` URIs.