perf(jqLite): don't use reflection to access expandoId

Since we allow only one copy of Angular to be loaded at a time it doesn't
make much sense randomly generate the expando property name and then be
forced to use slow reflective calles to retrieve the IDs.
fix(jqLite): change expando property to a more unique name

This was causing issue when element === window
A better strategy can be thought of later on.