Nuke CanvasPixelArray as it is dropped from WebKit as well.

lib/dom/idl/dart/dart.idl

 
 // This file introduces / supplements and forces Dart declarations.
 
 module default {
   NamedNodeMap implements sequence<Node>;
   NodeList implements sequence<Node>;
   HTMLCollection implements sequence<Node>;
   MediaList implements sequence<DOMString>;
   StyleSheetList implements sequence<StyleSheet>;
   TouchList implements sequence<Touch>;
-  CanvasPixelArray implements sequence<int>;
 
   Float32Array implements sequence<double>;
   Float64Array implements sequence<double>;
   Int8Array implements sequence<int>;
   Int16Array implements sequence<int>;
   Int32Array implements sequence<int>;
   Uint8Array implements sequence<int>;
   Uint16Array implements sequence<int>;
   Uint32Array implements sequence<int>;
 
@@ skipping 171 matching lines @@
   };
 
   [Supplemental]
   interface Uint8ClampedArray {
     // Avoid 'overriding static member BYTES_PER_ELEMENT'.
     [Suppressed] const long BYTES_PER_ELEMENT = 1;
 
     [Suppressed] void set();
     [DartName=setElements, Custom] void set(in any array, in optional unsigned long offset);
   };
-
-  [NumericIndexedGetter, CustomIndexedSetter]
-  interface CanvasPixelArray {
-    readonly attribute long length;
-  };
 };
 
 module storage {
   // TODO(vsm): Define new names for these (see b/4436830).
   [Supplemental]
   interface IDBCursor {
     [DartName=continueFunction] void continue(in optional IDBKey key);
   };
   [Supplemental]
   interface IDBIndex {
@@ skipping 27 matching lines @@
   [Supplemental, Callback] // Add missing Callback attribute.
   interface VoidCallback {
   };
 };
 
 module svg {
     interface SVGNumber {
       [StrictTypeChecking, Custom] attribute double value;
     };
 }