Remove unnecessary 'if' branch.

In Path::addPathForRoundedRect there is an'if' block testing a conditional 
that does the same step as the default flow. This patch removes the redundant 
test.

BUG=260260

Review URL: https://chromiumcodereview.appspot.com/19202002

git-svn-id: svn://svn.chromium.org/blink/trunk@154233 bbb929c8-8fbe-4397-9dbb-9b2b20218538