Merge pull request #9538 from oneeman/master

Fix typo in test name
Deduplicate HTMLBars / Handlebars Helper tests.

Finishes what was started in #9529.
Merge pull request #9532 from rwjblue/dedup-helper-tests

Deduplicate HTMLBars / Handlebars Helper tests.
[DOC] Grammar tweaks on computed property docs.
Merge pull request #9540 from markstory/computed-prop-docs

[DOC] Grammar tweaks on computed property docs.
Use embedded Handlebars version for HTMLBars compiler.
Merge pull request #9539 from rwjblue/build-stuff

Use embedded Handlebars version for HTMLBars compiler.
Add {{log}} helper to HTMLBars.
Add {{debugger}} helper.
Fix version constraint in composer.json
Merge pull request #9544 from aminin/master

Fix version constraint in composer.json
Merge pull request #9533 from rwjblue/log-helper

Add {{log}} and {{debugger}} helper for HTMLBars.
[Bugfix Beta] [Fixes #9541] components which subscribe to actions now throw if they fail to handle them.
Merge pull request #9547 from stefanpenner/components-subscribed-to-actions-are-noisy

[Fixes #9541] components which subscribe to actions now must handle them
Adds HTMLBars `loc` helper
Merge pull request #9537 from twokul/htmlbars-local-helper

Adds HTMLBars `loc` helper
[Bugfix Beta] Improve performance of Mixin creation by 50% -> 60% (when mixins are composed of multiple mixins)

* shape Mixin correctly (properties set in constructor)
* don’t pass arguments object around
* prefer new Mixin(args, properties) internally

This isn’t really going to have much of an impact by itself, but is part of a larger push  to improve the performance of our existing object model.
Partial and template HTMLBars helpers
Merge pull request #9552 from rwjblue/rebased-partial

Partial and template HTMLBars helpers.
Adds an ability to pass functions to `assert` and `deprecate`