Updated dom files and removed some IE only types

Updated the dom files according to new IE spec. Remove part of the IE
only types in "extensions.d.ts" that are not used in the new spec.

Author: zhengbli

.gitignore

@@ -46,3 +46,5 @@ scripts/*.js.map
 coverage/
 internal/
 **/.DS_Store
+src/lib/backup/dom.generated.d.ts
+src/lib/backup/webworker.generated.d.ts