Use CompileCache supportedExtensions instead of require.extensions

src/compile-cache.js

@@ -221,5 +221,5 @@ exports.install = function (nodeRequire) {
   })
 }
 
-
+exports.supportedExtensions = Object.keys(COMPILERS)
 exports.resetCacheStats()

src/package.coffee

@@ -503,7 +503,7 @@ class Package
           path.join(@path, @metadata.main)
         else
           path.join(@path, 'index')
-      @mainModulePath = fs.resolveExtension(mainModulePath, ["", _.keys(require.extensions)...])
+      @mainModulePath = fs.resolveExtension(mainModulePath, ["", CompileCache.supportedExtensions...])
 
   activationShouldBeDeferred: ->
     @hasActivationCommands() or @hasActivationHooks()