perf(@ngtools/webpack): reduce redudant module rebuilds when cache is restored
perf(@ngtools/webpack): reduce redudant module rebuilds when cache is restored

With this change we reduce the redundant module rebuilds when Webpack's FS cache is restored.

Previously, when the cache was restored we caused all modules to be rebuild even though their contents didn't change. This is because the file emit history wasn't persisted to disk.

This also caused the side effect that Webpack will create additional cache `pack` files due to the unnecessary module rebuilds, which ultimatly causes increase of the size of the cache on disk.

catull/angular-cli,geofffilippi/angular-cli,Brocco/angular-cli,clydin/angular-cli,angular/angular-cli,geofffilippi/angular-cli,geofffilippi/angular-cli,clydin/angular-cli,angular/angular-cli,clydin/angular-cli,clydin/angular-cli,Brocco/angular-cli,geofffilippi/angular-cli,catull/angular-cli,catull/angular-cli,Brocco/angular-cli,angular/angular-cli,Brocco/angular-cli,catull/angular-cli,angular/angular-cli,Brocco/angular-cli