Performance improvement: cache transformed source values so when watchify is used, we don't waste time regenerating sourcemaps for modules that haven't changed.
Performance improvement: cache transformed source values so when
watchify is used, we don't waste time regenerating sourcemaps for
modules that haven't changed.

royriojas/browserify-hmr,royriojas/browserify-hmr,sverrejoh/browserify-hmr,sverrejoh/browserify-hmr,AgentME/browserify-hmr,AgentME/browserify-hmr,AgentME/browserify-hmr,sverrejoh/browserify-hmr,royriojas/browserify-hmr