Fix handling of font stylesheets with non-HTTPS scheme or scheme-less URLs

[westonruter]

• When someone enqueues a font CDN stylesheet without the required HTTPS scheme, automatically supply it before checking against the regex and ensure the link has the HTTPS URL set during processing.
• Improve URL checking by first ensuring the host name matches.
• Ignore differences for URL scheme (even scheme-less URLs) when comparing URLs since the scheme is irrelevant.

Fixes #1072

[kienstra]

Hi @westonruter, thanks for this PR. I'm reviewing it now.

[kienstra]

Nice use of $this->assertEqualSets(), I didn't know about that.

[kienstra]

Approved

Hi @westonruter,
This pull request looks good, and it worked locally.

When enqueuing the Google Font file that @douglyuckling listed in #1072, the <link> appeared as expected, using both "Paired mode" (with a child theme of twentyten) and "Native AMP" (with the ampconf theme):

wp_enqueue_style( 'hemingway_googleFonts', '//fonts.googleapis.com/css?family=Raleway' );

Also, as expected, the <link> appeared with https, even if I changed the enqueuing URL to http://fonts...

[douglyuckling]

Yep, works for me, too. Thanks!