Closure Compiler by default will report diagnostics from type checks in
any JavaScript code, including code emitted by the Angular compiler.
Disabling `checkTypes` substantially reduces warning spam for users, and
allows them to run with stricter compiler flags (e.g. treating actual
diagnostics from user code as errors).
Closure Compiler will still type check the code and use types (where
found and correct) for optimizations.
PR Close#20828
4efc32dabf