[javascript] remove ajaxHtmlHead from dom response once it has been processed. This fixes #549138: treeview: folding is broken The new, systematic, pageid management (introduced by rev 37b376bb4088) made the treeview return : <ul class="treeview">...</ul> <div class="ajaxHtmlHead">...</div> which was then processed by getDomFromResponse and wrapped into a single div node : <div> <ul class="treeview">...</ul> <div class="ajaxHtmlHead">...</div> </div> In the treeview case, the node inserted into the tree was the wrapping <div> instead of the <ul>, causing the folding bug mentioned in the ticket.

msg isn't defined there, but we've to give traceback information to record error