Implementation of CSS3 nav-up/down/left/right properties from CSS3 UI.

Source/core/css/CSSGrammar.y.in

Index: Source/core/css/CSSGrammar.y.in
diff --git a/Source/core/css/CSSGrammar.y.in b/Source/core/css/CSSGrammar.y.in
index adcd2ad93e2d82af194a4152ad84923b02f2b411..37e6fa460599470eb38c722a9da0b79d59b6a629 100644
--- a/Source/core/css/CSSGrammar.y.in
+++ b/Source/core/css/CSSGrammar.y.in
@@ -1642,6 +1642,7 @@ term:
   | URI maybe_space { $$.id = CSSValueInvalid; $$.string = $1; $$.unit = CSSPrimitiveValue::CSS_URI; }
   | UNICODERANGE maybe_space { $$.id = CSSValueInvalid; $$.string = $1; $$.unit = CSSPrimitiveValue::CSS_UNICODE_RANGE; }
   | HEX maybe_space { $$.id = CSSValueInvalid; $$.string = $1; $$.unit = CSSPrimitiveValue::CSS_PARSER_HEXCOLOR; }
+  | IDSEL maybe_space { $$.id = CSSValueInvalid; $$.string = $1; $$.unit = CSSPrimitiveValue::CSS_STRING; }
   | '#' maybe_space { $$.id = CSSValueInvalid; $$.string = CSSParserString(); $$.unit = CSSPrimitiveValue::CSS_PARSER_HEXCOLOR; } /* Handle error case: "color: #;" */
   | VARFUNCTION maybe_space IDENT closing_parenthesis maybe_space {
       $$.id = CSSValueInvalid;