Implement Deque in LinkedList

Bug: issue 8512
Change-Id: Ic9a26c50a1b165ee32deb2e6941d3ba5e414abab
Added RegExp.quote(String) which returns an escaped string,
i.e., the escaped string can be used to create a RegExp that would 
match the non-escaped string as if it were a literal pattern.

Change-Id: I224443a6b4a37344e79b50b0bf5064cd75809936
Review-Link: https://gwt-review.googlesource.com/#/c/5870/
Removes some obsolute comments

Looks like these are leftover from DOM refactoring.

Change-Id: Icd91d742abe7f6500a782ce82c4e9e9234961788
Merge remote-tracking branch 'upstream/master'