[CSS Grid Layout] minmax() should be a CSSFunction instead of a CSSValueList
https://bugs.webkit.org/show_bug.cgi?id=127057

Source/WebCore:

Reviewed by Antti Koivisto.

We were incorrectly dumping minmax(x,y) as "x y" instead of
"minmax(x,y)". That's because we were treating minmax() internally
as a CSSValueList instead of a CSSFunction. Replaced that and also
added some extra information to our tests in order to check that
we don't regress. From now on the CSS grid layout testing helper
functions print not only the computed style but also the contents
of element.style.webkitGridDefinition{Columns|Rows}.

* css/CSSFunctionValue.h:
(WebCore::CSSFunctionValue::arguments):
* css/CSSParser.cpp:
(WebCore::CSSParser::parseGridTrackList):
(WebCore::CSSParser::parseGridTrackRepeatFunction):
(WebCore::CSSParser::parseGridTrackSize):
* css/CSSParser.h:
* css/StyleResolver.cpp:
(WebCore::createGridTrackSize):

LayoutTests:

Include the output of element.style.webkitGridDefinition{Columns|Rows}
as part of the expected output.

* fast/css-grid-layout/grid-columns-rows-get-set-expected.txt:
* fast/css-grid-layout/grid-columns-rows-get-set-multiple-expected.txt:
* fast/css-grid-layout/named-grid-line-get-set-expected.txt:
* fast/css-grid-layout/named-grid-line-get-set.html:
* fast/css-grid-layout/resources/grid-definitions-parsing-utils.js:
(testGridDefinitionsSetJSValues):
(testNonGridDefinitionsSetJSValues):
(checkGridDefinitionsSetJSValues):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@163013 268f45cc-cd09-0410-ab3c-d52691b4dbfc