Add a missing dependency on collection.

CHANGELOG.md

Index: CHANGELOG.md
diff --git a/CHANGELOG.md b/CHANGELOG.md
index ddfb455a99535d73c0a270d89b754b4ffa269278..f22eabacf5c58f28a3ae11098b2ac5330db6525d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,11 @@
+## 0.12.3+7
+
+* Add a missing dependency on the `collection` package.
+
 ## 0.12.3+6
 
+**This version was unpublished due to [issue 287][].**
+
 * Properly report load errors caused by failing to start browsers.
 
 * Substantially increase browser timeouts. These timeouts are the cause of a lot
@@ -8,10 +14,14 @@
 
 ## 0.12.3+5
 
+**This version was unpublished due to [issue 287][].**
+
 * Fix a crash when skipping tests because their platforms don't match.
 
 ## 0.12.3+4
 
+**This version was unpublished due to [issue 287][].**
+
 * The compact reporter will update the timer every second, rather than only
   updating it occasionally.
 
@@ -22,12 +32,18 @@
 
 ## 0.12.3+3
 
+**This version was unpublished due to [issue 287][].**
+
 * Limit the number of test suites loaded at once. This helps ensure that the
   test runner won't run out of memory when running many test suites that each
   load a large amount of code.
 
 ## 0.12.3+2
 
+**This version was unpublished due to [issue 287][].**
+
+[issue 287]: https://github.com/dart-lang/test/issues/287
+
 * Improve the display of syntax errors in VM tests.
 
 * Work around a [Firefox bug][]. Computed styles now work in tests on Firefox.