Avoid using transparency layer for fancy borders.

We paint transparent borders with radius on an offscreen layer. This is unnecessary and expensive especially for gpu rasterization. This patch simply removes the save-restore layer steps.

The border edges are now painted slightly differently. It is not wrong - just different. A few borders have color values that are off by one integral value, which was unexpected. This is a skia bug - skbug.com/2211.

BUG=343188

Review URL: https://codereview.chromium.org/165213005

git-svn-id: svn://svn.chromium.org/blink/trunk@167942 bbb929c8-8fbe-4397-9dbb-9b2b20218538