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

LayoutTests/fast/css-grid-layout/named-grid-line-get-set.html

Index: LayoutTests/fast/css-grid-layout/named-grid-line-get-set.html
diff --git a/LayoutTests/fast/css-grid-layout/named-grid-line-get-set.html b/LayoutTests/fast/css-grid-layout/named-grid-line-get-set.html
index b163ce77aca409362c5b80d336e096c20e6092bc..d5d09047002e32870a0a24d2ee89645b044057f0 100644
--- a/LayoutTests/fast/css-grid-layout/named-grid-line-get-set.html
+++ b/LayoutTests/fast/css-grid-layout/named-grid-line-get-set.html
@@ -66,6 +66,18 @@
     grid-template-columns: (first) (nav) 10px;
     grid-template-rows: 50px (nav nav2) (middle) 10px;
 }
+.gridWithAutoAsCustomIdent {
+    grid-template-columns: (auto) 10px 50px;
+    grid-template-rows: 50px (auto) 10px;
+}
+.gridWithMinmaxAsCustomIdent {
+    grid-template-columns: (minmax) 10px 50px;
+    grid-template-rows: 50px (minmax) 10px;
+}
+.gridWithSubgridAsCustomIdent {
+    grid-template-columns: (subgrid) 10px 50px;
+    grid-template-rows: 50px (subgrid) 10px;
+}
 </style>
 <script src="../../resources/js-test.js"></script>
 </head>
@@ -90,6 +102,9 @@
 <div class="grid gridWithUnbalancedParentheses" id="gridWithUnbalancedParentheses"></div>
 <div class="grid gridWithMisplacedParentheses" id="gridWithMisplacedParentheses"></div>
 <div class="grid gridWithContiguousParentheses" id="gridWithContiguousParentheses"></div>
+<div class="grid gridWithAutoAsCustomIdent" id="gridWithAutoAsCustomIdent"></div>
+<div class="grid gridWithMinmaxAsCustomIdent" id="gridWithMinmaxAsCustomIdent"></div>
+<div class="grid gridWithSubgridAsCustomIdent" id="gridWithSubgridAsCustomIdent"></div>
 
 <script src="resources/grid-definitions-parsing-utils.js"></script>
 <script>
@@ -131,6 +146,9 @@
     testGridDefinitionsValues(document.getElementById("gridWithUnbalancedParentheses"), "none", "none");
     testGridDefinitionsValues(document.getElementById("gridWithMisplacedParentheses"), "none", "none");
     testGridDefinitionsValues(document.getElementById("gridWithContiguousParentheses"), "none", "none");
+    testGridDefinitionsValues(document.getElementById("gridWithAutoAsCustomIdent"), "none", "none");
+    testGridDefinitionsValues(document.getElementById("gridWithMinmaxAsCustomIdent"), "none", "none");
+    testGridDefinitionsValues(document.getElementById("gridWithSubgridAsCustomIdent"), "none", "none");
 
     debug("");
     debug("Test getting and setting invalid grid-template-columns and grid-template-rows through JS");
@@ -140,6 +158,10 @@
     testGridDefinitionsSetBadJSValues("(foo (bar)) 10px", "50% ((baz bar) foo) 2em");
     testGridDefinitionsSetBadJSValues("(foo bar 10px", "50% (baz bar) foo) 2em");
     testGridDefinitionsSetBadJSValues("(foo 10px) 2em", "(50% bar) (foo)");
+    testGridDefinitionsSetBadJSValues("(foo auto) 2em", "50% (auto)");
+    testGridDefinitionsSetBadJSValues("10% (minmax nav)", "(minmax) 50% (minmax end)");
+    testGridDefinitionsSetBadJSValues("(start) 2em (subgrid)", "(subgrid) 2em");
+
 </script>
 </body>
 </html>