Do not add forwarding constructors to a pricate constructor from a different library.

sdk/lib/_internal/compiler/implementation/resolution/members.dart

Index: sdk/lib/_internal/compiler/implementation/resolution/members.dart
diff --git a/sdk/lib/_internal/compiler/implementation/resolution/members.dart b/sdk/lib/_internal/compiler/implementation/resolution/members.dart
index 42e2cc03774dc2a5fd2d2179984834a2f424ebee..5420dcae4799457624cf118c94a245b60e8c470c 100644
--- a/sdk/lib/_internal/compiler/implementation/resolution/members.dart
+++ b/sdk/lib/_internal/compiler/implementation/resolution/members.dart
@@ -4321,6 +4321,14 @@ class ClassResolverVisitor extends TypeDefinitionVisitor {
       if (!member.isGenerativeConstructor) return;
       FunctionElement forwarder =
           createForwardingConstructor(member, mixinApplication);
+      if (isPrivateName(member.name) &&
+          mixinApplication.library != superclass.library) {
+        // Do not create a forwarder to the super constructor, because the mixin
+        // application is in a different library than the constructor in the
+        // super class and it is not possible to call that constructor from the
+        // library using the mixin application.
+        return;
+      }
       mixinApplication.addConstructor(forwarder);
     });
     calculateAllSupertypes(mixinApplication);