Web updates

Service Workers 8e25c26efc93

Improve service worker script caching and update (#1283) This change includes/considers the following: - Include imported scripts to byte-check (for classic scripts). - Compare responses' body instead of source text as per - Handle duplicate importScripts() as per #1041. - Remove imported scripts updated flag referenced in importScripts() by using service worker's state item instead. - Have Update's perform the fetch steps cover module scripts. - Confirm dobule-download of imported scripts pointed out in never happens; importing a script again always gets the result from the cache. This change basically gets the imported scripts included to the byte-check for updates. Update continues with Install if any of the (main or imported) resources has been changed. This change also makes any duplicated requests (including the main script) from importScripts() return the result from the cache. Fixes #839, #1041, #1212, #1023.

Jungkee Song