Bump angular_compiler to 0.4.2.

I missed this in my original change.

PiperOrigin-RevId: 224882172

Author: alorenzen

angular_compiler/pubspec.yaml

@@ -2,7 +2,7 @@ name: angular_compiler
 author: Dart Team <[email protected]>
 homepage: https://github.com/dart-lang/angular
 description: Compiler for AngularDart.
-version: 0.4.1
+version: 0.4.2
 
 environment:
   sdk: ">=2.1.0-dev.5.0 <3.0.0"