Make arguments to Location.assign() and .replace() non-optional

http://whatwg.org/html#location

Firefox Nightly, IE11 Release Preview and Opera 12.16 all throw an
exception when these functions are called with no argument.

BUG=328194

Review URL: https://codereview.chromium.org/108213011

git-svn-id: svn://svn.chromium.org/blink/trunk@163852 bbb929c8-8fbe-4397-9dbb-9b2b20218538