Add property to CssStyleDeclaration to detect if a CSS value is available.

sdk/lib/_blink/dartium/_blink_dartium.dart

 /**
  * This library provides entry points to the native Blink code which backs
  * up the dart:html library.
  */
 library dart.dom._blink;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:html';
 import 'dart:_internal' hide Symbol, deprecated;
@@ skipping 693 matching lines @@
 
 class BlinkCSSStyleDeclaration {
   static $cssText_Getter(mthis) native "CSSStyleDeclaration_cssText_Getter";
 
   static $cssText_Setter(mthis, value) native "CSSStyleDeclaration_cssText_Setter";
 
   static $length_Getter(mthis) native "CSSStyleDeclaration_length_Getter";
 
   static $parentRule_Getter(mthis) native "CSSStyleDeclaration_parentRule_Getter";
 
+  static $__propertyQuery___Callback(mthis, name) native "CSSStyleDeclaration___propertyQuery___Callback_RESOLVER_STRING_1_DOMString";
+
   static $__setter___Callback(mthis, propertyName, propertyValue) native "CSSStyleDeclaration___setter___Callback";
 
   static $getPropertyPriority_Callback(mthis, propertyName) native "CSSStyleDeclaration_getPropertyPriority_Callback_RESOLVER_STRING_1_DOMString";
 
   static $getPropertyValue_Callback(mthis, propertyName) native "CSSStyleDeclaration_getPropertyValue_Callback_RESOLVER_STRING_1_DOMString";
 
   static $item_Callback(mthis, index) native "CSSStyleDeclaration_item_Callback_RESOLVER_STRING_1_unsigned long";
 
   static $removeProperty_Callback(mthis, propertyName) native "CSSStyleDeclaration_removeProperty_Callback_RESOLVER_STRING_1_DOMString";
 
@@ skipping 8778 matching lines @@
   // _DOMStringMap native entry  points
   static containsKey(_DOMStringMap, key) native "DOMStringMap_containsKey_Callback";
 
   static item(_DOMStringMap, key) native "DOMStringMap_item_Callback";
 
   static setItem(_DOMStringMap, key, value) native "DOMStringMap_setItem_Callback";
 
   static remove(_DOMStringMap, key) native "DOMStringMap_remove_Callback";
 
   static get_keys(_DOMStringMap) native "DOMStringMap_getKeys_Callback";
-}
+}