Update the pubspec's homepage link.

pkgs/stack_trace/pubspec.yaml

diff --git a/pkgs/stack_trace/pubspec.yaml b/pkgs/stack_trace/pubspec.yaml
index 4d9793d..8adfb2f 100644
--- a/pkgs/stack_trace/pubspec.yaml
+++ b/pkgs/stack_trace/pubspec.yaml
@@ -9,7 +9,7 @@
 # in pub to stay in sync with this.
 version: 1.1.1
 author: "Dart Team <misc@dartlang.org>"
-homepage: http://www.dartlang.org
+homepage: http://github.com/dart-lang/stack_trace
 description: >
   A package for manipulating stack traces and printing them readably.