* WIP merge from upstream google/blockly
* fixing some merging bugs. Getting the drag surface to work, updating some function calls, etc.
* make the trash can lid animate again and fix the cursor to show an x when things will be removed.
* Fix text rendering logic in fields
* Hand apply some more changes from blockly flyout.js to flyout_base.js.
Also revert 08efd1381c
in scratch-blocks since it breaks variables and there is more work fenichel is planning
to do here.
* Fix drop-down field rendering
* Resolve issue with text input field widths on init
* Remove unused blockly (built) files
* Remove unused language files
* Resolve lint issues and rebuild
* Add blockly build targets to cleanup script
* Return 0 if 'this.arrow_' does not exist in a dropdown field
* Remove unused / irrelevant comments
* Don't force text-centering around FIELD_WIDTH if arrow present
* Add dark arrow asset
* Refactor FieldNumber restrictor generator to be static
* Allow disabling of FieldDropDown colour changing
* Add FieldTextDropDown and FieldNumberDropDown
* Add number drop-downs to list blocks
* Add docs
* Update `setArgType` -> `addArgType`
* Ensure arrow only created once
* Update list index min
* Refactor shared components of num restriction
* Line breaks
* Clear touch identifier
* Clear touch identifier when text drop-down closed
* Inheritance simplification