Report messages instead of just printing.

pkg/front_end/lib/src/kernel_generator_impl.dart

Index: pkg/front_end/lib/src/kernel_generator_impl.dart
diff --git a/pkg/front_end/lib/src/kernel_generator_impl.dart b/pkg/front_end/lib/src/kernel_generator_impl.dart
index 2116a4954cab6eb2b03c28f9174b672f3953d0e6..60d6907a3db540e3430d49fe2daa4f80d04a18d1 100644
--- a/pkg/front_end/lib/src/kernel_generator_impl.dart
+++ b/pkg/front_end/lib/src/kernel_generator_impl.dart
@@ -147,7 +147,8 @@ Future<CompilerResult> generateKernelInternal(ProcessedOptions options,
     }
 
     if (kernelTarget.errors.isNotEmpty) {
-      kernelTarget.errors.forEach(options.deprecated_reportError);
+      // TODO(ahe): The errors have already been reported via CompilerContext.
+      kernelTarget.errors.forEach(options.reportMessage);
       return null;
     }
 
@@ -156,7 +157,7 @@ Future<CompilerResult> generateKernelInternal(ProcessedOptions options,
         program: program,
         deps: kernelTarget.loader.getDependencies());
   } on deprecated_InputError catch (e) {
-    options.deprecated_reportError(e.deprecated_format());
+    options.reportMessage(deprecated_InputError.toMessage(e));
     return null;
   } catch (e, t) {
     return reportCrash(e, t);