Fixes typos

Author: leonsenft

CHANGELOG.md

@@ -3,10 +3,10 @@
 * Adds support for shadow host selectors `:host()` and `:host-context()`.
 * Adds support for shadow-piercing descendant combinator `>>>` and its alias
   `/deep/` for backwards compatibility.
-* Adds support for non-functional IE filter properties (i.e. `filter: FlipH`)
-* Fixes emitted CSS for '@page' directive when body includes declarations and
+* Adds support for non-functional IE filter properties (i.e. `filter: FlipH`).
+* Fixes emitted CSS for `@page` directive when body includes declarations and
   page-margin boxes.
-* Exports `Message` from `parser.dart` so its no longer necessary to import
+* Exports `Message` from `parser.dart` so it's no longer necessary to import
   `src/messages.dart` to use the parser API.
 
 ## 0.13.2+2