Make MediaQueryMatcher::styleResolverChanged() not to call mainWorldScriptState() with null Frame

This patch changes MediaQueryMatcher::styleResolverChanged() not to call mainWorldScriptState() with null Frame. From beginning MediaQueryMatcher::styleResolverChanged() doesn't check whether Document::frame() is null or not even if Document::frame() can return null.

BUG=294829
TEST=n/a; hard to reproduce
R=haraken@chromium.org

Review URL: https://codereview.chromium.org/23902049

git-svn-id: svn://svn.chromium.org/blink/trunk@158088 bbb929c8-8fbe-4397-9dbb-9b2b20218538