Use new match Functor ElementTraversal API in  DOMSiblingTraversalStrategy

Use new match Functor ElementTraversal API in  DOMSiblingTraversalStrategy to
simplify the code a bit.

R=adamk@chromium.org, esprehn@chromium.org

Review URL: https://codereview.chromium.org/475023002

git-svn-id: svn://svn.chromium.org/blink/trunk@180299 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Change WebCore namespace to blink

Fix some leftovers after the WebCore -> blink namespace changes.

NOTRY=true

Review URL: https://codereview.chromium.org/477743003

git-svn-id: svn://svn.chromium.org/blink/trunk@180300 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Widen expectations for editing/spelling/spellcheck-editable-on-focus.html

Now also timing out on Mac/Debug, and it's consistently timing out,
not flakily.

BUG=356957
TBR=mkwst@chromium.org

Review URL: https://codereview.chromium.org/476843004

git-svn-id: svn://svn.chromium.org/blink/trunk@180301 bbb929c8-8fbe-4397-9dbb-9b2b20218538