Remove noisy warning.

pkg/front_end/lib/src/fasta/dill/dill_library_builder.dart

Index: pkg/front_end/lib/src/fasta/dill/dill_library_builder.dart
diff --git a/pkg/front_end/lib/src/fasta/dill/dill_library_builder.dart b/pkg/front_end/lib/src/fasta/dill/dill_library_builder.dart
index 31d96d513cefebdfca849b85673fdeca2b278cf2..22445eedef0fd9467b4b6144c45ad2dfbf2c4a1f 100644
--- a/pkg/front_end/lib/src/fasta/dill/dill_library_builder.dart
+++ b/pkg/front_end/lib/src/fasta/dill/dill_library_builder.dart
@@ -89,7 +89,6 @@ class DillLibraryBuilder extends LibraryBuilder<KernelTypeBuilder, Library> {
     if (name == "_exports#") {
       // This is a hack / work around for storing exports in dill files. See
       // [compile_platform.dart](../compile_platform.dart).
-      print("$uri: _exports# not implemented yet.");
     } else {
       addBuilder(name, new DillMemberBuilder(member, this), member.fileOffset);
     }