Change link drag bubble to take directionality into account

Change DragImage to use drawBidiText instead of drawText for the link
text thereby respecting the directionality. Also check the paragraph
directionality explicitly to allow proper alignment.

Also, move the determineDirectionality functionality out of HTMLElement
and into a new BidiTextRun file allowing the functionality to be shared.

BUG=287263
R=leviw@chromium.org

Review URL: https://codereview.chromium.org/123573003

git-svn-id: svn://svn.chromium.org/blink/trunk@164454 bbb929c8-8fbe-4397-9dbb-9b2b20218538