It appears that this exceptional case was only valid for IE<8 and that for IE>=8 it
was actually causing a bug with the `ng-href-attr` directive on `<a>` elements.

Closes #5479

Prior to this fix, $parse/$eval would return 'null' if a middle key in
an expression's value is null, when it should be expected to be undefined.

This patch tries to remedy this by returning undefined for middle values in
expressions, when fetching a child of that null value.

For example:

```js
// Given the following object:
$scope.a = {
  b: null
};

// $scope.$eval('a.b.c') returns undefined, whereas previously it would return null
```

Closes #5480

Before this fix, the xlink:href property of an SVG <a> element could not be parsed
on click, as the property is an SVGAnimatedString rather than a DOMString.

This patch parses the xlink:href's animVal into a DOMString in order to prevent
an `Object #<SVGAnimatedString> has no method 'indexOf'` exception from being thrown,
and also to update the location if necessary as expected.

Closes #5472
Closes #5198
Closes #5199
Closes #4098
Closes #1420

Use a faster path when the number of path tokens is low (ie the common case).
This results in a better than 19x improvement in the time spent in $parse and
produces output that is about the same speed in chrome and substantially faster
in firefox.
http://jsperf.com/angularjs-parse-getter/6

Closes #5359

Workaround for chrome for android until #2129 is ready.

Closes #5308, #5323

When `multiple` attribute is set on a `<select>` control and the model value is an empty array,
we should invalidate the control.  Previously, this directive was using incorrect logic for
determining if the model was empty.

Closes #5337

allow and pass through new line characters when checking passed in expression

Closes #5000

jQuery's elem.html('') is way slower than elem.empty(). As clearing
element contents happens quite often in certain scenarios, switching
to using .empty() provides a significant performance boost when using
Angular with jQuery.

Closes #4457

Change the a directive to link and hookup a click event only when
there is no href or name in the template element.
In a large Google app, this results in about 800 fewer registrations,
saving a small but measurable amount of time and memory.

Closes #5362