chore(Angular.js): Use call and === instead of apply and == in type check functions

Updates isDate et al to use call instead of apply and === instead of ==.
The change to call brings minor performance improvement and === is just
better practice than ==.
http://jsperf.com/call-vs-apply-tostring

Closes #5295
fix(isElement): return boolean value rather than `truthy` value.

angular.isElement currently returns a truthy object/function, or false. This
patch aims to correct this behaviour by casting the result of the isElement
expression to a boolean value via double-negation.

Closes #4519
Closes #4534
fix($compile): update cloned elements if the template arrives after the cloning

If an element has a directive whose content is loaded using `templateUrl`,
and the element is cloned using a linking function before the template arrives,
the clone needs to be updated as well.

This also updates `ngIf` and `ngRepeat` to keep the connection to the clone
of a tranclude function, so that they know about the changes a directive with
`templateUrl` does to the element in the future.

Fixes to #4930.
docs(CHANGELOG): add v1.2.4 changes
chore(release): cut 1.2.4 wormhole-blaster release
revert: chore($resource): Use shallow copy instead of angular.copy
revert: chore(Angular.js): Use call and === instead of apply and == in type check functions
chore(CHANGELOG): remove reverted commits from 1.2.4
chore(release): start 1.2.5 singularity-expansion iteration
docs($injector): add example on how to use the element.injector

Closes #5188
chore(CHANGELOG): introduce perf() section for performance-related commits

Instead of using fix() or chore() when labelling a commit which improves
speed or performance use perf(). Perf commits will be listed in the
CHANGELOG under "Performance Improvements".

For example:
perf($animate): cache all getComputedStyle operations to reduce additional reflows
docs(guide/forms): clarify how NgModelController can be added to scope

Closes #5200
docs(tutorial): enlarge clickable area of tutorial nav buttons

Change position of <a> and <li> tags in tutorial nav buttons
partial. This allows the full area of the button to be clicked
rather than just the text.

Closes #5074
Closes #5209
docs(contribute) add platform agnostic git install link

Closes #5216
docs($q): correct typo in the 'Differences Q/$q' section

Closes #5230
docs($route): clarify examples of route parameters

Putting route parameter examples in braces was misleading newcomers.

Closes #5243
docs(input): remove redundant closing span tag

Closes #5257
style($route): make jshint happy

Fix the broken build and earn a late (french spelling).
docs(design): guide index formatting

Just my first pass at a more readable format of the guide index.

Note: the styles apply to all content in the docs, not just the guide
index. This is intentional and I feel that the result is positive.
docs(TRIAGING): Labels cla yes/no are automatically set

The labels are set by a script and
should not be set manually any more.