The build optimizer passes that are still relevant for Ivy are now implemented as babel plugins. Using babel has several advantages. The `babel-loader` is already present within the build pipeline and many packages will already need to be processed by it. The `babel-loader` also provides the necessary infrastructure to setup babel and link it to the Webpack build system. This removes the need for the infrastructure code within the build optimizer loader and reduces the build optimizer to only a set of transformation plugins for babel to consume. The babel plugin architecture also allows for less code to represent similar transformations and provides a variety of helper utilities which further reduces the amount code needed.
The passes are now implemented to be safer when transforming code. Enum values which contain potential side effects are also no longer altered. Enums are wrapped in less destructive manner which reduces the likelihood of incorrectly emitting the transformed enum. Class static fields which contain potential side effects are no longer wrapped in pure annotated IIFEs. Known safe Angular static fields are also wrapped and Angular static fields which are not required in production code are also dropped.
The conversion of the passes not only reduces the amount of code to maintain but also provides a noticeable performance improvement. Initial tests of a production build of AIO resulted in a ~10% total build time reduction.
Closes#12160
When using the `statsJson` browser builder option, the resulting JSON data is now streamed into a file instead of written in one large block. This mitigates crashes due to the generated string exceeded the Node.js limit.
