a bit verbose, but lets ensure we don’t deoptimize these functions in some runtimes.

* passing arguments object to another function (other then via apply) deoptimizes function body
* materializing the arguments object via splice deoptimizes the function body
Merge pull request #2320 from stefanpenner/perf

a bit verbose, but lets ensure we don’t deoptimize these functions in so...
added note about coalescing and custom URLs
Temporary fix for #2344 rollback after delete for recordArrays

This is a temporary fix, it's clear this code needs to be refactored.
Moreover I am not sure that removing deleted records from recordArrays
before they are deleted is a correct design decision.
warn instead of throw when resolving keys to model

Before this commit, if you had a payload like:

```javascript
{
  “posts”: []
}
```

But didn’t have a “post” model defined, Ember
Data would blow up. As discussed in the data
team meeting, we decided to warn if the model
could not be resolved. In this spirit,
Ember Data just doesn’t process what it doesn’t
understand, but can still provide you with a
better debugging message to give you hints on
what your payload should look like.

fixes GH-2337
Merge pull request #2346 from emberjs/dont-assert-model-types-on-payload-in-production

warn instead of throw when resolving keys to model
Merge pull request #2371 from emberjs/fix_rollback_record_arrays

Temporary fix for #2344 rollback after delete for recordArrays
Merge pull request #2370 from H1D/coalescing_docs

added note about coalescing and custom URLs
Rollback after delete record failure

failing test for #2344
Merge pull request #2359 from sly7-7/rollback-after-save-error

Rollback after delete record failure