Remove no-op code in SkAlphaRuns::add

The old code says

        runs += x + 1;
        alpha += x + 1;
        x = 0;
        lastAlpha += x; // we don't want the +1

The last line does nothing. Remove this unnecessary line.

BUG=skia:401

Review URL: https://codereview.chromium.org/1506253002
1 file changed