update changelog for Dartium roll

CHANGELOG.md

Index: CHANGELOG.md
diff --git a/CHANGELOG.md b/CHANGELOG.md
index c38a97d15ff2844031df7eff6f7b57d772f83f16..cfda762c4f6671a11b93c845a7a1518e61785524 100644
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+++ b/CHANGELOG.md
@@ -23,6 +23,15 @@
     `SecurityContext.usePrivateKeyBytes`, for use as the password for PKCS12
     data.
 
+### Dartium
+
+  * The Chrome-based tools that ship as part of the Dart SDK – Dartium and
+    content shell – are now based on Chrome version 45 (instead of Chrome 39).
+  * Dart browser libraries (`dart:html`, `dart:svg`, etc) have not been updated.
+    * These are still based on Chrome 39.
+    * These APIs will be updated in a future release.
+  * Something about experimental APIs?...

[kevmoo, 2016/03/03 19:02:52]

Terry: do we have idea about the experimental APIs that no longer work? Can we
give an example?

[Alan Knight, 2016/03/03 19:20:40]

Note that there are experimental APIs which have changed in the underlying
browser, and will not work with the older libraries. For example,
Element.animate.

[kevmoo, 2016/03/03 19:41:34]

Done.

+
 ### Service protocol changes
 
 * Fixed a documentation bug where the field `extensionRPCs` in `Isolate`