[BUGFIX beta] Still update HTML5 history if the previous state was null

Fixes #3195, Closes #3580
Uses document.contains to figure if element exists in the DOM

addresses issue raised in
https://github.com/Polymer/ShadowDOM/issues/365#issuecomment-33509711
[BUGFIX beta] HashLocation no longer looks the hash up with location.hash because of a Firefox decode bug. Fixes #4262
[FEATURE ember-routing-inherits-parent-model] Route inherits parent's model by default.
Merge pull request #4246 from locks/model-inheritance

Route inherits parent's model by default.
mark hbs code samples as such
Merge pull request #4300 from ibroadfo/patch-1

mark hbs code samples as such
Don't deoptimize every Ember.run

TryCatchStatements are currently non-optimizable statements in v8 (and likely other run times). Additionally, methods containing try/catch statements are not inlineable

Although Ember.run's shouldn't be in a tight loop, we should incur the deopt penalty if we don't even use Ember.onerror
Merge pull request #4310 from stefanpenner/dont-deopt-every-ember-run

Don't deoptimize every Ember.run
remove extra and unneeded closures.
Merge pull request #4311 from stefanpenner/reduce-closures

remove extra and unneeded closures.
remove un-needed toString
Merge pull request #4313 from stefanpenner/remove-uneeded-to-string

remove un-needed toString
[FEATURE ember-eager-url-update] link-to should generate the url if it eagerly updates it, not use href because it includes rootURL. Fixes #1244
Merge pull request #4312 from jayphelps/link-to-update-url

[FEATURE ember-eager-url-update] link-to should generate the url if it eagerly updates it, not use the href because it includes rootURL. Fixes #1244
Merge pull request #4297 from jayphelps/location-hash-decode

[BUGFIX beta] HashLocation no longer looks the hash up with location.hash because of a Firefox decode bug. Fixes #4262
[BUGFIX beta] Support Handlebars ~> 1.0.

Ember is compatible with Handlebars versions from 1.0.0 forward.
Merge pull request #4316 from rjackson/unlock-handlebars-version

[BUGFIX beta] Support Handlebars ~> 1.0.
[NICETHING beta] prevent value= with input type='select'

Fixes #4319
Merge pull request #4321 from machty/prevent-checkbox-value-dumbletons

[NICETHING beta] prevent value= with input type='select'