Return after throwing an exception when ConvolerNode.buffer rate is wrong.

If the exception for the incorrect sample rate was caught, we still
continued and set the buffer to the wrong thing.  We need to return
after throwing the exception.

BUG=352776
TEST=dom-exceptions.html updated with test

Review URL: https://codereview.chromium.org/1074463003

git-svn-id: svn://svn.chromium.org/blink/trunk@193389 bbb929c8-8fbe-4397-9dbb-9b2b20218538
3 files changed