WASM work etc.

Testing in the 2.2 releases, public final in 2.5

Remaining items, after initial PR lands:

• Add multi window support to the web driver #2740
• Add mouse wheel support to web driver #2744
• Handle file saving dialog as a file download in the web driver #2738
• Add file open dialog for the web driver #2737
• Add OpenURL support to the web driver #2736
• Add notification support to the web driver #2735
• Add persistent settings and preferences capability to Web driver #2734
• Implement storage APIs for web driver #4634

(omitted some items that are optional :) )