Compute logicalVisualOverflowRect once in InlineTextBox::paint.

Previously it was computed twice in a row, and
this showed up in a CPU profile.

Review URL: https://codereview.chromium.org/341093004

git-svn-id: svn://svn.chromium.org/blink/trunk@176563 bbb929c8-8fbe-4397-9dbb-9b2b20218538