added IE11 fixes (reverted reverted commit)

This reverts commit 036a35af81e3ed5340dcab5f2f89752e4e88cb5f.
added workround for history.back issue on IE11 (bugid:110595)
Update selection restore logic for IE11. bugid:110582 bugid:110584
Update selection restore logic in popup for IE11. bugid:110582 bugid:110584
Avoid an error while doing "Toggle HTML Edit Mode". bugid:110642
Fallback to the empty string if no content is given. bugid:110643