[IE9] Don't send link share password placeholder
[IE9] Don't send link share password placeholder

When exiting the password field in the share dialog, IE9 would
mistakenly think that the password has changed and would send the
placeholder.

This fix prevents changing the password whenever the placeholder is set
as value.

lrytz/core,lrytz/core,lrytz/core,lrytz/core,lrytz/core