Fix some problems reported by clang static analyzer

These changes fix code paths where variable writes are done that have no effect later on, or code paths that do nothing.

Review URL: https://codereview.chromium.org/101763008

git-svn-id: svn://svn.chromium.org/blink/trunk@164628 bbb929c8-8fbe-4397-9dbb-9b2b20218538