Reapply "Make Map constructors return LinkedHashMap."
Reapply "Make Map constructors return LinkedHashMap."

Updated tests assuming a specific ordering of an unlinked hash map
to not be daft.

R=floitsch@google.com, jmesserly@google.com

Review URL: https://codereview.chromium.org//22859069

git-svn-id: ba870c207403ed87e84e4e2f3f91276ef01d69f6@26693 260f80e4-7a28-3924-810f-c04153c831b5

serates/csslib,dart-lang/csslib,yjbanov/csslib,serates/csslib,dart-lang/csslib,yjbanov/csslib