Pass index into computed array callbacks
Unify observer/observes implementation

This is similar to the implementation of FunctionPrototype.property /
Ember.computed.  Now when the Ember.observer function is modified the
function prototype will already of the correct behavior.
Merge pull request #4821 from rondale-sc/unify_observer_observes_implementation

Unify observer/observes implementation
Cache length in observesBefore for loop
Use one variable assignment per declaration.
[FEATURE ember-handlebars-compiler-ast-to-precompile] Allow precompile to accept an already existing Handlebars AST

[FEATURE pass-ast-to-precompile] Adding feature flags

[FEATURE pass-ast-to-precompile] Changing flag name
[BUGFIX] fillIn helper should take context into consideration
Merge pull request #5352 from teddyzeenny/fix-fillin

[BUGFIX] fillIn helper should take context into consideration
Merge pull request #5341 from chadhietala/pass-ast

[FEATURE pass-ast-to-precompile] Allow precompile to accept AST
Merge pull request #5350 from cibernox/fix_cache_length

Cache length in observesBefore for loop
Add missing tests for Ember.DAG

I am not sure sure hoy to tag fixing the absence of tests.
Merge pull request #5354 from cibernox/test_ember_dag

Add missing tests for Ember.DAG
Merge pull request #5351 from rwjblue/single-line-var-declarations

Use one variable assignment per declaration.
Ensure that variable assigning declarations are single line
Merge pull request #5355 from rwjblue/metal-single-line-assigning-declarations

Ensure that variable assigning declarations are single line
ember-runtime single var assignment per declaration

I am working through a code style cleanup effort using
[jscs](https://github.com/mdevils/node-jscs) rules.

You can see the script and rules in:
https://github.com/rwjblue/ember.js/compare/code-style-rules
Merge pull request #5356 from rwjblue/single-line-var-runtime

ember-runtime single var assignment per declaration
ember-application single var assignment per declaration
Merge pull request #5357 from rwjblue/single-var-line-ember-application

ember-application single var assignment per declaration
[BUGFIX beta]

In 1.6 Ember.computed.empty was updated to
automatically respect arrays without forcing
users to use array.[] as the dependent key.

Ember.computed.notEmpty was not updated.

This commit fixes that.