refactor($ngAnimate): simplify the animation event rewrite

To avoid code duplication, use single variables for keeping
properties/events names to use. Also, fix some errors that have
happened after the rewrite from moment ago.
chore($ngAnimate): simplify vendor prefixes handling in tests
fix(dateFilter): allow negative millisecond value strings
chore: remove Firefox CORS workaround

See #1468
fix($httpBackend): don't send empty string bodies

The `XMLHttpRequest.send` spec defines different semantics for `null`
than for an empty String: an empty String should be sent with a
`Content-Type` of `text/plain`, whereas `null` should have no
`Content-Type` header set.

Closes #2149
fix($animator): avoid completing the animation asynchronously unless CSS transtiions/animations are present

Closes #4023
Closes #3940
chore(grunt): switch to the new //# sourceMappingURL pragma

All browsers except from Chrome implemented both the old
"//@ sourceMappingURL" and the new "//# sourceMappingURL" pragmas
in the same version so the only reason to keep the old one was Chrome.
However, Chrome 29, i.e. current stable version already supports
the new pragma so there's no need to wait any longer.
fix($httpBackend): set headers with falsy values

This is a breaking change. To migrate to the new behavior,
delete or set headers to `undefined` to avoid having them sent.
To restore the old behavior, override `$httpBackendProvider`
with the old implementation.

Closes #2984
docs(ngRoute): add angularEvent param to $routeChangeStart event

Adds missing implied first argument, `angularEvent`, to match
the rest of the `$routeChange` event documentation.
fix($compile): allow interpolations for non-event handlers attrs

Fix wrong behaviour that didn't allow 'data-on' and 'on' element attributes
to be interpolated by $compile. The regex now accepts any string beginning
with 'on' and with at least one more English letter.
feat($compile): support tel: links in a[href]

Allow `tel:` links so that click-to-call works in mobile browsers
test($sce): make ie8 happy

Ref: https://github.com/angular/angular.js/pull/4221#/issuecomment-25515813

Closes #4221
style($qSpec): add semi-colons
style(rootScopeSpec): add semi-colons
fix(*): protect calls to hasOwnProperty in public API

Objects received from outside AngularJS may have had their `hasOwnProperty`
method overridden with something else. In cases where we can do this without
incurring a performance penalty we call directly on Object.prototype.hasOwnProperty
to ensure that we use the correct method.

Also, we have some internal hash objects, where the keys for the map are provided
from outside AngularJS. In such cases we either prevent `hasOwnProperty` from
being used as a key or provide some other way of preventing our objects from
having their `hasOwnProperty` overridden.

BREAKING CHANGE: Inputs with name equal to "hasOwnProperty" are not allowed inside
form or ngForm directives.

Before, inputs whose name was "hasOwnProperty" were quietly ignored and not added
to the scope.  Now a badname exception is thrown.

Using "hasOwnProperty" for an input name would be very unusual and bad practice.
Either do not include such an input in a `form` or `ngForm` directive or change
the name of the input.

Closes #3331