https://github.com/angular/angular.js/commit/fb6062fb9d83545730b993e94ac7482ffd43a62c implements a
fix for NaN values causing $watchCollection to throw an infdig error. This change updates the test
by adding an assertion which explains what is actually being tested a bit better, and may also
provide better information in the event that the test ever fails.

Closes #6758

$watchCollection checks if oldValue !== newValue which does not work for NaN. This was causing
infinite digest errors, since comparing NaN to NaN in $watchCollection would always return false,
indicating that a change was occuring on each loop.

This fix adds a simple check to see if the current value and previous value are both NaN, and
if so, does not count it as a change.

Closes #4605

In Firefox, hovering over an option in an open select menu updates the selected property of option
elements. This means that when a render is triggered by the digest cycle, and the list of options
is being rendered, the selected properties are reset to the values from the model and the option
hovered over changes. This fix changes the code to only use DOM elements' selected properties in a
comparison when a change event has been fired. Otherwise, the internal new and existing option
arrays are used.

Closes #2448
Closes #5994

The orderBy filter now allows string predicates passed to the orderBy filter to make use property
name predicates containing non-ident strings, such as spaces or percent signs, or non-latin
characters.

This behaviour requires the predicate string to be double-quoted.

In markup, this might look like so:

```html
<div ng-repeat="item in items | orderBy:'\"Tip %\"'">
...
</div>
```

Or in JS:

```js
var sorted = $filter('orderBy')(array, ['"Tip %"', '-"Subtotal $"'], false);
```

Closes #6143
Closes #6144

This change brings Angular's JSONP behaviour closer in line with jQuery's. It will no longer treat
a callback called with no data as an error, and will no longer support IE8 via the onreadystatechanged
event.

BREAKING CHANGE:

Previously, the JSONP backend code would support IE8 by relying on the readystatechanged events. This
is no longer the case, as these events do not provide adequate useful information for deeming whether
or not a response is an error.

Previously, a JSONP response which did not pass data into the callback would be given a status of -2,
and treated as an error. Now, this situation will instead be given a status of 200, despite the lack
of data. This is useful for interaction with certain APIs.

Previously, the onload and onerror callbacks were added to the JSONP script tag. These have been
replaced with jQuery events, in order to gain access to the event object. This means that it is now
difficult to test if the callbacks are registered or not. This is possible with jQuery, using the
$.data("events") method, however it is currently impossible with jqLite. This is not expected to
break applications.

Closes #4987
Closes #6735

Android 4.3 only supports webkitCancelRequestAnimationFrame.

Closes #6526

In order to make the behavior compatible with $rootScope.$watch and $rootScope.$on methods, and
make it possible to deregister an attribute observer, Attributes.$observe method now returns a
deregistration function instead of the observer itself.

BREAKING CHANGE: calling attr.$observe no longer returns the observer function, but a
    deregistration function instead.

    To migrate the code follow the example below:

    Before:

```
    directive('directiveName', function() {
      return {
        link: function(scope, elm, attr) {
          var observer = attr.$observe('someAttr', function(value) {
            console.log(value);
          });
        }
      };
    });
```

    After:

```
    directive('directiveName', function() {
      return {
        link: function(scope, elm, attr) {
          var observer = function(value) {
            console.log(value);
          };

          attr.$observe('someAttr', observer);
        }
      };
    });
```

Closes #5609

Originally we destroyed the oldValue by incrementaly copying over portions of the newValue
into the oldValue during dirty-checking, this resulted in oldValue to be equal to newValue
by the time we called the watchCollection listener.

The fix creates a copy of the newValue each time a change is detected and then uses that
copy *the next time* a change is detected.

To make `$watchCollection` behave the same way as `$watch`, during the first iteration
the listener is called with newValue and oldValue being identical.

Since many of the corner-cases are already covered by existing tests, I refactored the
test logging to include oldValue and made the tests more readable.

Closes #2621
Closes #5661
Closes #5688
Closes #6736

Closes #5012

PR #5547 introduced conversion of all 0 status codes to 404 for cases
where no response was recieved (previously this was done for the
file:// protocol only). But this mechanism is too eager and
masks legitimate cases where status 0 should be returned. This commits
reverts to the previous mechanism of handling 0 status code for the
file:// protocol (converting 0 to 404) while retaining the returned
status code 0 for all the protocols other than file://

Fixes #6074
Fixes #6155