Bug 1103697: Revert line that shouldn't have changed in bug 1093862's 2....

...1 merge, to hopefully restore callscreen functionality. r=drs

This commit reverts a line of context that was accidentally (I assume) changed in a merge, introducing an undeclared variable.

See https://bugzilla.mozilla.org/show_bug.cgi?id=1103697#c2 (and subsequent bug-comment) for more info/analysis.  I suspect this will fix bug 1103697 (but we should fix it regardless).