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

LayoutTests/fast/css-grid-layout/resources/grid-definitions-parsing-utils.js

Index: LayoutTests/fast/css-grid-layout/resources/grid-definitions-parsing-utils.js
diff --git a/LayoutTests/fast/css-grid-layout/resources/grid-definitions-parsing-utils.js b/LayoutTests/fast/css-grid-layout/resources/grid-definitions-parsing-utils.js
index ca22800a8238f2fd6582717f2418b9deab6c9b06..55348bf71d19bca49d916c606ebc0d7ac5cf15f6 100644
--- a/LayoutTests/fast/css-grid-layout/resources/grid-definitions-parsing-utils.js
+++ b/LayoutTests/fast/css-grid-layout/resources/grid-definitions-parsing-utils.js
@@ -35,13 +35,25 @@ function checkGridDefinitionsSetJSValues(useGrid, columnValue, rowValue, compute
     document.body.removeChild(element);
 }
 
-function testGridDefinitionsSetBadJSValues(columnValue, rowValue)
+function checkGridDefinitionsSetBadJSValues(useGrid, columnValue, rowValue)
 {
     window.element = document.createElement("div");
     document.body.appendChild(element);
+    if (useGrid)
+        element.style.display = "grid";
     element.style.gridTemplateColumns = columnValue;
     element.style.gridTemplateRows = rowValue;
     // We can't use testSetJSValues as element.style.gridTemplateRows returns "".
     testGridDefinitionsValues(element, "none", "none");
     document.body.removeChild(element);
-}
+}
+
+function testGridDefinitionsSetBadJSValues(columnValue, rowValue)
+{
+    checkGridDefinitionsSetBadJSValues(true, columnValue, rowValue);
+}
+
+function testNonGridDefinitionsSetBadJSValues(columnValue, rowValue)
+{
+    checkGridDefinitionsSetBadJSValues(false, columnValue, rowValue);
+}