Leading/trailing whitespace in directive attributes with scope "&" is lost

[ChristopherBrix]

When I create a directive with an attribute which scope is defined with &, leading and trailing whitespaces are lost (fiddle).

While it can be circumvented by creating a variable and passing the evaluated variable as the value (using attribute={{variable}}, see the fiddle), this looks like a bug to me.

The fiddle uses Angular 1.4.9, but it's still present in the current snapshot v1.5.6-build.4785+sha.707664a

[gkalpak]

So, this has been the case since v1.0.0-rc.2 (8af4fde). I labelled this as a bug, but it could be expected behavior as well.

This is been around for so long, that I am not sure it is worth changing now.
If anyone wants to submit a PR, the problem "starts" at compile.js#L1887.

[Narretz]

I think this is similar to #11859