These two polyfill solutions that (re-)enable the Android 2.x browser with multitouch came up just recently:
MTFix and WebView MultiTouch Polyfill (WMP)
However, both polyfills will require you to provide an Android app container for download via the market. If that isn't a problem (i'd be happy to provide one), you could still have a pure online game, so when a user agent string containing a specific 2.x series webkit version is detected, you simply make a notice/direct link to the app container to download for 2.x users.
As both were developed with the priority intent to get pinch zooming working (which both solutions successfully do), there is still a lot of device testing to be done and opportunity for optimisation to be realised.
Therefore, speaking for the WMP project - it'd be great any HTML5 game developers would test and share their experiences, ideas and criticism by filing bug reports and questions on the Github page for WMP.