Fixes rendering errors when RRD file names contain IPv6 addresses and the
colon (":") characters are triple escaped.
Adapts the Lua-specific fix in #4340 to Javascript.
Signed-off-by: Philip L. McMahon <philip.l.mcmahon@gmail.com>
(cherry picked from commit d44302b3ac7a5f687c4a2bb6707cc3d922651f82 of PR #4358)