Message: Class constructor BindingLanguage cannot be invoked without 'new'

**I'm submitting a bug report**
The issues occurs when using "aurelia-framework": "1.2.0" and started when the aurelia-binding@2.1.6 was published.

* **Library Version:**
major.minor.patch-pre

**Please tell us about your environment:**
* **Operating System:**
Windows 10

* **Node Version:**
v6.10.2

* **NPM Version:**
3.10.10

* **JSPM OR Webpack AND Version**
JSPM 0.16.32 | webpack 2.1.0-beta.17

* **Browser:**
Chrome latest

* **Language:**
Javascript

**Current behavior:**
Binding engine throws error = Message: Class constructor BindingLanguage cannot be invoked without 'new'

**Expected/desired behavior:**
Binding engine should not throw exception

* **What is the expected behavior?**

* **What is the motivation / use case for changing the behavior?**

Start by reproducing the BindingLanguage constructor error with aurelia-framework 1.2.0 and aurelia-binding 2.1.6 in the reported Node, JSPM or webpack, and Chrome environment. Trace where the binding engine invokes BindingLanguage and confirm the fix by showing that the binding engine no longer throws the exception.

Written by the indexing model from the issue text.