Make sure a profiling range is started for every handled signal
Make sure a profiling range is started for every handled signal

If we allow an endRange() without a startRange() before the range
nesting can get confused. Also, it's enough to check the existence
of the profiler once.

Change-Id: I255675d6e23505b6f29196c0470892f6d778e7b4
Reviewed-by: Simon Hausmann <a975102812d593b3191088e3d0aeaeb6f11dbcf5@digia.com>

mgrunditz/qtdeclarative-2d,qmlc/qtdeclarative,qmlc/qtdeclarative,mgrunditz/qtdeclarative-2d,qmlc/qtdeclarative,qmlc/qtdeclarative,mgrunditz/qtdeclarative-2d,mgrunditz/qtdeclarative-2d,qmlc/qtdeclarative,mgrunditz/qtdeclarative-2d,qmlc/qtdeclarative,mgrunditz/qtdeclarative-2d,qmlc/qtdeclarative,qmlc/qtdeclarative,mgrunditz/qtdeclarative-2d