Change BidiResolver helper methods to take run list as argument

Change BidiResolver and InlineBidiResolver helper methods to take the
bidi run list as an argument instead of using m_runs and mark methods as
const where appropriate.

This is the first step towards reversing the ownership of the run list
and removing the m_runs member from BidiResolver.

BUG=396963
R=dglazkov@chromium.org

Review URL: https://codereview.chromium.org/410393002

git-svn-id: svn://svn.chromium.org/blink/trunk@178821 bbb929c8-8fbe-4397-9dbb-9b2b20218538