Fix DoubleLinkedQueue so that appending to entries also update the queue length.

Fix DoubleLinkedQueue so that appending to entries also update the queue length.

The extra non-queue features of this class are probably unnecessary, and are not proper naming (some functions should be getters).

Keeping unchanged for backwards compatibility, but it should probably either be removed or be suitably updated for 2.0.

BUG= http://dartbug.com/22802
R=sgjesse@google.com

Committed: https://code.google.com/p/dart/source/detail?r=44451

[Lasse Reichstein Nielsen, 2015-03-12 14:05:51]

lrn@google.com changed reviewers:
+ sgjesse@google.com

[Søren Gjesse, 2015-03-13 07:44:25]

lgtm

[Lasse Reichstein Nielsen, 2015-03-13 09:41:13]

Committed patchset #3 (id:40001) manually as 44451 (presubmit successful).