fix some errors in our SDK, mostly around numbers

tool/input_sdk/private/js_array.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of dart._interceptors;
 
 /**
  * The interceptor class for [List]. The compiler recognizes this
  * class as an interceptor, and changes references to [:this:] to
  * actually use the receiver of the method, which is generated as an extra
@@ skipping 280 matching lines @@
     if (!growable) markFixedList(list);
     return new JSArray<E>.typed(list);
   }
 
   Set<E> toSet() => new Set<E>.from(this);
 
   Iterator<E> get iterator => new ListIterator<E>(this);
 
   int get hashCode => Primitives.objectHashCode(this);
 
-  int get length => JS('JSUInt32', r'#.length', this);
+  int get length => JS('int', r'#.length', this);
 
   void set length(int newLength) {
     if (newLength is !int) throw new ArgumentError(newLength);
     if (newLength < 0) throw new RangeError.value(newLength);
     checkGrowable('set length');
     JS('void', r'#.length = #', this, newLength);
   }
 
   E operator [](int index) {
     if (index is !int) throw new ArgumentError(index);
@@ skipping 13 matching lines @@
 }
 
 /**
  * Dummy subclasses that allow the backend to track more precise
  * information about arrays through their type. The CPA type inference
  * relies on the fact that these classes do not override [] nor []=.
  */
 class JSMutableArray<E> extends JSArray<E> implements JSMutableIndexable {}
 class JSFixedArray<E> extends JSMutableArray<E> {}
 class JSExtendableArray<E> extends JSMutableArray<E> {}