Update V8 to version 3.27.9.1 (merged r21405).

TBR=machenbach@chromium.org

Review URL: https://codereview.chromium.org/296003006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@271883 0039d316-1c4b-4281-b951-d872f2087c98

DEPS

@@ -51,7 +51,7 @@ vars = {
   # the commit queue can handle CLs rolling Skia
   # and V8 without interference from each other.
   "v8_branch": "trunk",
-  "v8_revision": "21393",
+  "v8_revision": "21406",
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling WebRTC
   # and V8 without interference from each other.