fix($location) : initialize locationPrototype.$$absUrl to empty string

[GuillaumeSalles]

What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)
Initialize locationPrototype.$$absUrl to avoid a crash when base href and current location have different domains.

What is the current behavior? (You can also link to an open issue here)
#11091

What is the new behavior (if this is a feature change)?
Does not crash anymore.

Does this PR introduce a breaking change?
I don't think so...

Please check if the PR fulfills these requirements

• The commit message follows our guidelines: https://github.com/angular/angular.js/blob/master/CONTRIBUTING.md#commit-message-format
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

Other information:

Closes #11091

[googlebot]

We found a Contributor License Agreement for you (the sender of this pull request), but were unable to find agreements for the commit author(s). If you authored these, maybe you used a different email address in the git commits than was used to sign the CLA (login here to double check)? If these were authored by someone else, then they will need to sign a CLA as well, and confirm that they're okay with these being contributed to Google.

[googlebot]

We found a Contributor License Agreement for you (the sender of this pull request), but were unable to find agreements for the commit author(s). If you authored these, maybe you used a different email address in the git commits than was used to sign the CLA (login here to double check)? If these were authored by someone else, then they will need to sign a CLA as well, and confirm that they're okay with these being contributed to Google.

[GuillaumeSalles]

Hi, I just signed the CLA.

[gkalpak]

Seems reasonable, but one can never be too sure with $location stuff 😛
/cc @petebacondarwin for the final LGTM

(The CLA thing doesn't seem to have worked btw...)

[GuillaumeSalles]

I signed the CLA with another account. My mistake.
I just signed it again with the right email.

[googlebot]

CLAs look good, thanks!

[googlebot]

CLAs look good, thanks!

[gkalpak]

This should also fix #13565.

[petebacondarwin]

LGTM