fix(codegen): add explicit any to class fields

fixes #8204

Closes #8205

modules/angular2/src/compiler/output/ts_emitter.ts

@@ -130,6 +130,8 @@ class _TsEmitterVisitor extends AbstractEmitterVisitor implements o.TypeVisitor
     if (isPresent(field.type)) {
       ctx.print(`:`);
       field.type.visitType(this, ctx);
+    } else {
+      ctx.print(`: any`);
     }
     ctx.println(`;`);
   }