blink: Add backdrop-filter support

Source/core/css/parser/CSSPropertyParser.cpp

 /*
  * Copyright (C) 2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Nicholas Shanks <webkit@nickshanks.com>
  * Copyright (C) 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2012 Adobe Systems Incorporated. All rights reserved.
  * Copyright (C) 2012 Intel Corporation. All rights reserved.
  *
@@ skipping 1015 matching lines @@
     case CSSPropertyWebkitBoxFlex:
         validPrimitive = validUnit(value, FNumber);
         break;
     case CSSPropertyWebkitBoxFlexGroup:
         validPrimitive = validUnit(value, FInteger | FNonNeg);
         break;
     case CSSPropertyWebkitBoxOrdinalGroup:
         validPrimitive = validUnit(value, FInteger | FNonNeg) && value->fValue;
         break;
     case CSSPropertyWebkitFilter:
+    case CSSPropertyBackdropFilter:
         if (id == CSSValueNone)
             validPrimitive = true;
         else {
             RefPtrWillBeRawPtr<CSSValue> val = parseFilter();
             if (val) {
                 addProperty(propId, val, important);
                 return true;
             }
             return false;
         }
@@ skipping 7061 matching lines @@
         }
     }
 
     if (!list->length())
         return nullptr;
 
     return list.release();
 }
 
 } // namespace blink