Support consecutive slash operators for border-image value

Source/core/css/parser/CSSGrammar.y

 %{
 
 /*
  *  Copyright (C) 2002-2003 Lars Knoll (knoll@kde.org)
  *  Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All rights reserved.
  *  Copyright (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  *  Copyright (C) 2008 Eric Seidel <eric@webkit.org>
  *  Copyright (C) 2012 Intel Corporation. All rights reserved.
  *
  *  This library is free software; you can redistribute it and/or
@@ skipping 332 matching lines @@
 %type <boolean> decl_list
 %type <boolean> declaration
 %type <boolean> declarations_and_margins
 
 %type <boolean> prio
 
 %type <integer> match
 %type <integer> unary_operator
 %type <integer> maybe_unary_operator
 %type <character> operator
+%type <character> slash_operator
 
 %type <valueList> expr
 %type <value> term
 %type <value> unary_term
 %type <value> function
 %type <value> calc_func_term
 %type <character> calc_func_operator
 %type <valueList> calc_func_expr
 %type <valueList> calc_func_paren_expr
 %type <value> calc_function
@@ skipping 1222 matching lines @@
     }
     | expr operator term {
         $$ = $1;
         $$->addValue(makeOperatorValue($2));
         $$->addValue(parser->sinkFloatingValue($3));
     }
     | expr term {
         $$ = $1;
         $$->addValue(parser->sinkFloatingValue($2));
     }
+    | expr slash_operator slash_operator term {
+        $$ = $1;
+        $$->addValue(makeOperatorValue($2));
+        $$->addValue(makeOperatorValue($3));
+        $$->addValue(parser->sinkFloatingValue($4));
+    }    
   ;
 
 expr_recovery:
     error error_location error_recovery {
         parser->reportError($2, PropertyDeclarationCSSError);
     }
   ;
 
+slash_operator:
+     '/' maybe_space {
+         $$ = '/';
+     }
+  ;
+
 operator:
-    '/' maybe_space {
-        $$ = '/';
-    }
+    slash_operator
   | ',' maybe_space {
         $$ = ',';
     }
   ;
 
 term:
   unary_term maybe_space
   | unary_operator unary_term maybe_space { $$ = $2; $$.fValue *= $1; }
   | STRING maybe_space { $$.id = CSSValueInvalid; $$.isInt = false; $$.string = $1; $$.unit = CSSPrimitiveValue::CSS_STRING; }
   | IDENT maybe_space { $$ = makeIdentValue($1); }
@@ skipping 224 matching lines @@
     ;
 
 rule_error_recovery:
     /* empty */
   | rule_error_recovery error
   | rule_error_recovery invalid_square_brackets_block
   | rule_error_recovery invalid_parentheses_block
     ;
 
 %%