Fix documentation for cancel method of Ember.TextSupport
[BUGFIX release] `Ember.keys` should return own property

In IE8, `Ember.keys` couldn't return property that named the same as
own prototype property.
[BUGFIX release] Fix to return `undefined` for `href` of {{link-to}}

The old IE renders `false` to `href="false"` against my expectation.
[BUGFIX release] `Ember.Object.extend` should allow any prorerty
Merge pull request #3507 from tricknotes/fix-link-to-helper-for-old-ie

[BUGFIX release] Fix to return `undefined` for `href` of {{link-to}}
Update documentation for "customEvents"

The "loadedmetadata" event is no longer considered a bubbling event, and subsequently it will never be triggered.
[BUGFIX beta] Don't use incompatible array methods

The old IE doesn't have some `Array` methods.
Merge pull request #3511 from kanongil/patch-1

Update documentation for "customEvents"
Merge pull request #3508 from tricknotes/fix-object-extend-for-old-ie

[BUGFIX release] Fix Ember.Object.extend for old IE
Merge pull request #3506 from tricknotes/fix-for-old-ie

[BUGFIX beta] Don't use incompatible array methods
Merge pull request #3504 from lackac/patch-1

Fix documentation for cancel method of Ember.TextSupport
[BUGFIX beta] link-to, bound helper issues with arrays of primitives

/cc @kselden

Fixes #3342. Fixes #3429.
Merge pull request #3513 from machty/bound-primitives

[BUGFIX beta] link-to, bound helper issues with arrays of primitives
Refactor `Ember.Application.initializer`.

Previously, `Ember.Application.initializers` was implemented as a
concatenated property, which is works at class definition and instance
creation time, but not when the field is mutated, which is what
`Ember.Application.initializer` was doing prior to this commit.

Also reverted concatenatedProperties change, which had been added to try
unsuccessfully to address this issue.