[cssom] getComputedStyle for inline style and multiple globals

[zcorpan]

See
https://lists.w3.org/Archives/Public/www-style/2014Dec/0137.html
https://bugzilla.mozilla.org/show_bug.cgi?id=1109033
jquery/jquery#2622

Test
http://software.hixie.ch/utilities/js/live-dom-viewer/saved/4279
http://software.hixie.ch/utilities/js/live-dom-viewer/saved/4280

Apparently the inline style should be applied. (And getComputedStyle when called on an element from another global needs to consider style changes for that element, although how that works isn't really defined yet.)

[zcorpan]

Test case: multiple-globals.zip

[zcorpan]

Discussion on www-style
https://lists.w3.org/Archives/Public/www-style/2016Jun/0183.html

[FremyCompany]

Merging with #1548
(as far as I can see the behavior of all browsers was the same on these two saved doms)