DIP 1025--Dynamic Arrays Only Shrink, Never Grow--Community Review Round 1

[Walter Bright]

On 11/11/2019 12:50 PM, Meta wrote:
> Would it be enough to put an assert in GC.realloc/extend/free that asserts the 
> memory is GC-owned, maybe tied to a compiler switch?

Currently, for `a~=b` if `a` is not owned by the GC, it is copied to a new GC 
location by the runtime.