Initialize selection at (1,1) instead of (0,0)

Code with a similar purpose was added in 568e0e5701 but got lost
when some things were moved from ve.Surface to ve.ce.Surface in
5012ed10.

Initializing the selection at (0,0) was known to cause problems before,
and since 789d0caf093b breaks editing of empty documents: typing in an
empty document begins in an inline slug, but SurfaceObserver doesn't
notice typing in an inline slug unless the ce.Surface pawns it, which
is OK because insertions in slugs are always pawned, but the pawning
logic believes the cursor to be at offset 0 where there is no slug
(it's at offset 1) and so it doesn't pawn.

Bonus: update tests and add descriptions for dm.Surface.change tests

Change-Id: Id72314d0fe650dacc7cdb842f5cea2f3bfba5145
(cherry picked from commit 29a955bc0199edc4e21572f68db826aaa0e14356)
Fix check for preformatted when stripping whitespace

Previous was checking by string match to 'preformatted' which didn't
match 'mwPreformatted'. Now using node factory to see if
hasSignificantWhitespace is set.

Bug: 54083
Change-Id: I1be2d4568df7848e08074d200fb374acd508f6fa
(cherry picked from commit e7aed52d933686ac23afab1426bac644f0699c97)
Merge "Initialize selection at (1,1) instead of (0,0)" into wmf/1.22wmf17