docs(forms): fix code example for a custom form control

Closes #1021
docs(guide): fix typos in unit test guide
revert: fix(a): prevent Opera from incorrectly navigating on link click

This reverts commit c81d8176cc55cd15acae05259ead73f90a01f0b7.

This commit causes several issues (#1651, #1674, #1662) and doesn't even
contain a test that proves that anything on Opera got actually fixed.

If the original Opera resurfaces, we'll fix it properly.
refactor($browser): remove faulty 20+ cookies warning

the warning is defunct (and the test is incorrect) so obviously nobody is using
it and it just takes up space.

also the browser behavior varies (ff and chrome allow up to 150 cookies, safari
even more), so it's not very useful.

Closes #1712
fix($injector): remove bogus fn arg

getService fn takes only one argument, removing the second one.

Closes #1711
fix(jqLite): make next() ignore non-element nodes

next() is supposed to return the next sibling *element* so it
should ignore text nodes. To achieve this, nextElementSibling()
should be used instead of nextSibling().
fix(jqLite): children() should only return elements

The jQuery implementation of children only returns child nodes of the given element that are elements themselves. The previous jqLite implementation was returning all nodes except those that are text nodes. Use jQLite.contents() to get all the child nodes.

The jQuery implementation of contents returns [] if the object has no child nodes.  The previous jqLite implementation was returning undefined, causing a stack overflow in test/testabilityPatch.js when it tried to `cleanup()` a window object.

The testabilityPatch was incorrectly using children() rather than contents() inside cleanup() to iterate down through all the child nodes of the element to clean up.
Update docs/content/misc/faq.ngdoc

Updated the canonical video to a recent one. Fixed a typo.
upstream merge