reflect: enable allocation tests
reflect: enable allocation tests

They were disabled due to the lack of escape analysis. Now that
we have escape analysis, unskip these tests.

Change-Id: I79bf1e00342cf3d8969c9135c1ea5f7d3cb48f4d
Reviewed-on: https://go-review.googlesource.com/86248
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

golang/gofrontend,golang/gofrontend,golang/gofrontend,golang/gofrontend