fix(protractor) fix stack traces for WebElement errors

When angular/protractor@3c0e727136ab3d397c1a9a2bb02692d0aeb9be40
refactored `element()` into the ElementFinder object, the function lost
some of its error handling.  This removed references to frames inside
tests (`it()` blocks), making it hard to tell where the error was
actually occurring.

This commit fixes these problems, showing full stack traces for
WebElement errors.