[CSS Grid Layout] Disallow using <ident> and function names as <custom-ident>

[CSS Grid Layout] Disallow using <ident> and function names as <custom-ident>

As mentioned in this thread
http://lists.w3.org/Archives/Public/www-style/2014Feb/0734.html both
"subgrid" and "auto" idents and "minmax" function should be considered as
invalid <custom-idents>. This means that trying to use them as grid line
names in grid-template-{columns|rows} should be considered a grammar
violation making the whole declaration invalid.

While updating the test cases I found that we were not setting
"display:grid" in some tests, so I fixed that too.

[svillar, 2014-02-28 10:52:30]

Updated the description, I forgot to add a title for the issue.

[Julien - ping for review, 2014-03-01 00:42:21]

https://codereview.chromium.org/179383003/diff/1/Source/core/css/parser/Bison...
File Source/core/css/parser/BisonCSSParser-in.cpp (right):

https://codereview.chromium.org/179383003/diff/1/Source/core/css/parser/Bison...
Source/core/css/parser/BisonCSSParser-in.cpp:4682: ||
equalIgnoringCase(identValue->string, "subgrid"))
subgrid will be moved to level 2
(http://lists.w3.org/Archives/Public/www-style/2014Feb/0047.html) so I wouldn't
handle them here as the syntax could change too.

Note that this is not totally right AFAICT: <custom-ident> is supposed to match
the context in which the rule is called and <line-names> is called for several
properties with different grammars. An example is grid-template that should also
ban 'none'.

The change is not handling css-wide keywords here
(http://dev.w3.org/csswg/css-values-3/#common-keywords) such as 'initial' and
'inherit' along with 'default'.

I would have liked to have us solve this issue once and for all as this is going
to be required for other properties. Ideally we would want this generated from
the grammar (really long term goal). In the short-run, we will have to
pre-populate common keywords and then add the rule-specific keywords as we
parse.

[svillar, 2015-11-12 16:07:07]

Closing as this requires engine-wide actions