Commits

@angular-devkit/build-angular (0.900.0-rc.9)
Commit	Description	Notes
	emit error when a script is not found	[Closes #16659]
	change css optimizer from clean-css with cssnano	[Closes #16123] [Closes #13854]
	update tree-kill dependency to 1.2.2
	improve quality of differential loading sourcemaps
	replace istanbul-instrumenter-loader with coverage-istanbul-loader	[Closes #16576] [Closes #7117]
@angular-devkit/build-optimizer (0.900.0-rc.9)
Commit	Description	Notes
	revert to using TS 3.6
	improve quality of sourcemaps

Special Thanks

Alan Agius, Charles Lyding, Filipe Silva, Minko Gechev