Removed unnecessary memory allocation from Instancer::instanceContext().
Removed unnecessary memory allocation from Instancer::instanceContext().

This knocks nearly 20% off the runtime for the hashing of the bounds, and should have similar benefits elsewhere.

ImageEngine/gaffer,boberfly/gaffer,ImageEngine/gaffer,lucienfostier/gaffer,andrewkaufman/gaffer,appleseedhq/gaffer,hradec/gaffer,hradec/gaffer,boberfly/gaffer,goddardl/gaffer,ImageEngine/gaffer,andrewkaufman/gaffer,chippey/gaffer,cedriclaunay/gaffer,appleseedhq/gaffer,lucienfostier/gaffer,johnhaddon/gaffer,GafferHQ/gaffer,hradec/gaffer,andrewkaufman/gaffer,chippey/gaffer,boberfly/gaffer,lucienfostier/gaffer,chippey/gaffer,chippey/gaffer,ivanimanishi/gaffer,boberfly/gaffer,cedriclaunay/gaffer,cedriclaunay/gaffer,ivanimanishi/gaffer,johnhaddon/gaffer,GafferHQ/gaffer,lucienfostier/gaffer,appleseedhq/gaffer,cedriclaunay/gaffer,GafferHQ/gaffer,goddardl/gaffer,hradec/gaffer,goddardl/gaffer,goddardl/gaffer,ivanimanishi/gaffer,appleseedhq/gaffer,ivanimanishi/gaffer,johnhaddon/gaffer,GafferHQ/gaffer,johnhaddon/gaffer,ImageEngine/gaffer,andrewkaufman/gaffer,GafferHQ/gaffer,hradec/gaffer,johnhaddon/gaffer,andrewkaufman/gaffer