* fix: add isBlockCreatable to IFlyout interface
* fix: add getClickTarget to IToolboxItem interface
* fix: fix some types in zelos renderer
* fix: add scrollToStart to IFlyout interface
* fix: add setVisible_ to IToolboxItem
* fix: use instanceof check for workspace comments in gesture code
* fix: data stored on the DOM for tooltips
* fix: use blockSvg to access icons
* fix: add instanceof check in shortcut_items.js
* fix: suppress warning about onKeyDown in tolbox
* fix: add instanceof check in workspace_svg
* fix: don't use dot accessor to avoid type problem
* fix: silence type errors in ast_node.js