Regenerate tests
Make Array.size() a function instead of a property

Also add a deprecated extension property to help migration. This is done to
unify getting size of arrays and collections
Use newly built compiler for kotlin2js instead of bootstrap

Otherwise it's impossible to make any change in built-ins: the bootstrap
compiler is not able to compile the new stdlib because stdlib is designed to
compile against the built-ins of the same version, but bootstrap compiler is
only aware of old built-ins which it has in its classpath
Minor, fix formatting in Arrays.kt in stdlib
Make Array.indices extension property, move to stdlib

This is not something that needs to be intrinsified. Note that compiler
optimizations are still possible and the fact whether 'indices' is a member or
an extension is irrelevant to the optimizer