lib: improve module loading performance

This commit improves module loading performance by at least ~25-35%
in the module-loader benchmarks.

Some optimization strategies include:
* Try-finally/try-catch isolation
* Replacing regular expressions with manual parsing
* Avoiding unnecessary string and array creation
* Avoiding constant recompilation of anonymous functions and
function definitions within functions

PR-URL: https://github.com/nodejs/node/pull/5172


Reviewed-By: James M Snell <jasnell@gmail.com>