Fix exception in error processing; implement mapUri

pkg/analysis_server/lib/src/domain_execution.dart

Index: pkg/analysis_server/lib/src/domain_execution.dart
diff --git a/pkg/analysis_server/lib/src/domain_execution.dart b/pkg/analysis_server/lib/src/domain_execution.dart
index 9d83cbab9951a96f220151473206bb5d3a8bd915..9fb599fb5096562be9aa5752518540aff3acda70 100644
--- a/pkg/analysis_server/lib/src/domain_execution.dart
+++ b/pkg/analysis_server/lib/src/domain_execution.dart
@@ -103,12 +103,11 @@ class ExecutionDomainHandler implements RequestHandler {
             'Either file or uri must be provided, but not both');
       }
       Source source = server.getSource(path);
-      // TODO(brianwilkerson) Figure out how to perform the mapping.
-      String uri = '';
+      String uri = context.sourceFactory.restoreUri(source).toString();
       return new ExecutionMapUriResult(uri: uri).toResponse(request.id);
     } else if (params.uri != null) {
-      // TODO(brianwilkerson) Figure out how to perform the mapping.
-      String file = '';
+      Source source = context.sourceFactory.forUri(params.uri);
+      String file = source.fullName;
       return new ExecutionMapUriResult(file: file).toResponse(request.id);
     }
     return new Response.invalidParameter(