Remove generated directories with 100s of files.

client/html/generated/html/dartium/History.dart

-
-class _HistoryImpl extends _DOMTypeBase implements History {
-  _HistoryImpl._wrap(ptr) : super._wrap(ptr);
-
-  int get length() => _wrap(_ptr.length);
-
-  Dynamic get state() => _wrap(_ptr.state);
-
-  void back() {
-    _ptr.back();
-    return;
-  }
-
-  void forward() {
-    _ptr.forward();
-    return;
-  }
-
-  void go(int distance) {
-    _ptr.go(_unwrap(distance));
-    return;
-  }
-
-  void pushState(Object data, String title, [String url = null]) {
-    if (url === null) {
-      _ptr.pushState(_unwrap(data), _unwrap(title));
-      return;
-    } else {
-      _ptr.pushState(_unwrap(data), _unwrap(title), _unwrap(url));
-      return;
-    }
-  }
-
-  void replaceState(Object data, String title, [String url = null]) {
-    if (url === null) {
-      _ptr.replaceState(_unwrap(data), _unwrap(title));
-      return;
-    } else {
-      _ptr.replaceState(_unwrap(data), _unwrap(title), _unwrap(url));
-      return;
-    }
-  }
-}