Move ParseUnaryExpression into ParserBase and add tests.

This also makes PreParser produce the strict_delete error the same way as
Parser (see test).

R=rossberg@chromium.org
BUG=

Review URL: https://codereview.chromium.org/203193004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@20077 ce2b1a6d-e550-0410-aec6-3dcde31c8c00