fix(angular-loader): do not depend on "closure" globals that are not available in `angular-loader`

[gkalpak]

I'm submitting a ...

• bug report
• feature request
• other (Please do not submit support requests here (see above))

Current behavior:
Commits such as cf43ccd and a0641ea (possibly others) have changed stringify.js in ways that do not take into account the fact that it is also included in angular-loader where it does not have access to all th necessary "closure" globals available in angular.js.
Fortunately, this bug only appears when there are errors to be thrown.

Expected / new behavior:
Files that are included in angular-loader should not break by trying to access properties/functions that are not available in angular-loader.

Angular version: At least 1.3.3+

Browser: all