Otherwise, script56.chm's javascript will keep reloading the image and
triggering onload events non-stop. It protects against this using a variable
"noReentry", which is only set temporarily while setting the source, so it
expects it to be triggered synchronously.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=53927Signed-off-by: Gabriel Ivăncescu <gabrielopcode@gmail.com>