Can't use Closure Compiler if node.js detected

[kryger]

Since 2.0.0 node.js is automatically detected in the env and used if available. This makes it impossible to use Closure Compiler when node.js is available:

Error: optimizer with name of "closure" not found for this environment

I believe there are three solutions:

1. Add a configuration flag to disable autodetecting node.js
2. If optimize: 'closure' detected, always use Rhino to prevent the error
3. Use node.js for tracing dependencies but Rhino for minification if Closure Compiler used (I doubt it's technically possible since that's handled by r.js, but perhaps someone will come up with ideas?)

[kryger]

I see the behaviour was essentially introduced in commit 26450a8 , the original pull request from @skwakman included the runner config option. Perhaps reconsidering it as an optional flag would be an acceptable solution?

Currently upgrading to 2.0.0 breaks the build for projects that use Closure Compiler in environments with node.js installed.