fix(@ngtools/webpack): export VirtualFileSystemDecorator type
fix(@ngtools/webpack): export VirtualFileSystemDecorator type

We shouldn't need to export this, but webpack-rollup-loader uses it.

Brocco/angular-cli,clydin/angular-cli,filipesilva/angular-cli,angular/angular-cli,angular/angular-cli,geofffilippi/angular-cli,geofffilippi/angular-cli,beeman/angular-cli,filipesilva/angular-cli,ocombe/angular-cli,clydin/angular-cli,Brocco/angular-cli,Brocco/angular-cli,ocombe/angular-cli,Brocco/angular-cli,beeman/angular-cli,clydin/angular-cli,filipesilva/angular-cli,ocombe/angular-cli,catull/angular-cli,geofffilippi/angular-cli,ocombe/angular-cli,beeman/angular-cli,clydin/angular-cli,geofffilippi/angular-cli,angular/angular-cli,catull/angular-cli,beeman/angular-cli,ocombe/angular-cli,catull/angular-cli,filipesilva/angular-cli,Brocco/angular-cli,angular/angular-cli,catull/angular-cli