Change BreakingContext to specify direction for width calculations

Update BreakingContext:handleText to specify the text direction when
constructing text runs and measuring width.

BUG=333004
R=dglazkov@chromium.org

Review URL: https://codereview.chromium.org/132033004

git-svn-id: svn://svn.chromium.org/blink/trunk@164807 bbb929c8-8fbe-4397-9dbb-9b2b20218538