Fix style issues in RenderBlockLineLayout::stripTrailingSpaces

Follow up for r183716, fixing style in stripTrailingSpace.

R=pdr@chromium.org

Review URL: https://codereview.chromium.org/654283002

git-svn-id: svn://svn.chromium.org/blink/trunk@183759 bbb929c8-8fbe-4397-9dbb-9b2b20218538