perf(@ngtools/webpack): reduce source file and Webpack module iteration
perf(@ngtools/webpack): reduce source file and Webpack module iteration

During a build, the number of iterations over both the TypeScript program's source files and Webpack's modules has been reduced. Both of these collections can contain a significant number of elements especially in larger applications.

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