Rename Cell properties to avoid name clashes in type inference.

sdk/lib/_internal/compiler/js_lib/collection_patch.dart

Index: sdk/lib/_internal/compiler/js_lib/collection_patch.dart
diff --git a/sdk/lib/_internal/compiler/js_lib/collection_patch.dart b/sdk/lib/_internal/compiler/js_lib/collection_patch.dart
index 0d56162c9cff540fbb3d68595e37a7360a041e6b..67e54bc0978c6367684ee3b35025e006361add9f 100644
--- a/sdk/lib/_internal/compiler/js_lib/collection_patch.dart
+++ b/sdk/lib/_internal/compiler/js_lib/collection_patch.dart
@@ -544,7 +544,7 @@ class _LinkedIdentityHashMap<K, V> extends JsLinkedHashMap<K, V> {
     int length = JS('int', '#.length', bucket);
     for (int i = 0; i < length; i++) {
       LinkedHashMapCell cell = JS('var', '#[#]', bucket, i);
-      if (identical(cell.key, key)) return i;
+      if (identical(cell.hashMapCellKey, key)) return i;
     }
     return -1;
   }
@@ -589,7 +589,7 @@ class _LinkedCustomHashMap<K, V> extends JsLinkedHashMap<K, V> {
     int length = JS('int', '#.length', bucket);
     for (int i = 0; i < length; i++) {
       LinkedHashMapCell cell = JS('var', '#[#]', bucket, i);
-      if (_equals(cell.key, key)) return i;
+      if (_equals(cell.hashMapCellKey, key)) return i;
     }
     return -1;
   }